Issei Hyoudou/Relationships

Issei has developed many relationships throughout the series, both within the Occult Research Club and the Three Factions. He has also attracted the attention of most of the female characters.

Rias Gremory
She is the woman who reincarnated Issei. When she first summoned him, she treated him as a "special" case, knowing that he had a lot of potential. As time went on, she later started to fall in love with him. The initial reason (if any) is unknown. She and Issei both shared their first kiss with each other following the latter's duel with Riser. She often gets jealous when other girls flirt with or tempt him. She loves him very much and is willing to do anything with him. In response, Issei will do anything to protect her, as he loves her just as much as she loves him. One time, she even tried to have sex with him just to get out of an arranged marriage.

To add to that, Issei constantly wakes up sleeping next to her naked. For this reason, she says that she has no problem with letting Issei see her naked and even let him touch her breasts from time to time, which she constantly says she has no problem with.

In Volume 10, Issei was given permission from Rias' mother to start a harem to keep the girls happy. During this time Issei was struggling to overcome the trauma that was caused by Raynare. This trauma is the reason why Issei is unable to call a girl by her first name as well as why he simply cannot believe that the women around him would actually be attracted to him. This causes tension to form between Rias and Issei until he proclaims his love for her in front of the audience during the rating game. She was completely heartbroken by the news of Issei's death (which Sairaorg berates her for), but gained a great deal of hope when she found out that his spirit was still alive through his Evil Pieces. It also appears that when Issei sees her breasts or touches them, he gains a tremendous amount of power, which helped him achieve Balance Breaker (Volume 5) and Trident (Volume 9), and also replenished his depleted stamina and energy. This, however, has resulted in her gaining derogatory nicknames such as "Switch Princess" (Bikou) and "Crimson Bust Princess" (Azazel). At the end of Volume 10, Rias and Issei end up becoming an official couple.

Asia Argento
Issei is very protective of Asia ever since he met her, pitying the girl's suffering and was greatly saddened when she was killed by Raynare. Issei views Asia as a little sister that he needs to protect and is willing to fight anyone that as much tried to hurt her such as Raynare, Freed Sellzen and Diodora Astaroth. In fact, when Asia was supposingly killed by Shalba, the negative emotion of losing Asia made Issei enter the Juggernaut Drive and brutally beat up Shalba to near death.

Issei often has lecherous thoughts about her, but he tries to block these thoughts, believing that he must protect her from everyone, including himself, and tries to make himself think of her as a little sister, until later on, their relationship strengthens and rather than seeing her as his little sister, Issei starts seeing her as a single girl and a woman, this happened due to the fact that both of them kissed each other at the end of Volume 6 in the light novels.

Akeno Himejima
When Akeno first met Issei, she thought of him as a cute kouhai that she could spoil and flirt with, but as time went on, she started to see that Issei was very kind and caring, eventually falling in love with him in Volume 4.

Despite continually vying with the other girls for his affection, she finally declares her love for him in Volume 7 after he helped her reconciled her relationship with her father. She loves him a great deal and isn't afraid to get into fights over him with the other girls as she does get jealous, though she is a lot more calm about it than Rias and the others. She is fine with the belief that she is third in his harem after Rias and Asia, as she likes the idea of an affair. She was so heartbroken when she thought that Issei had died, that she disconnected herself from reality, remembering only the times that she spent with Issei, and cried terribly with her father. She, along with everyone else, later regained hope after finding out that Issei's spirit was alive.

Koneko Toujou
At first, Koneko disliked Issei due to his lecherous mind and antics, but started to like him after seeing his determination and tenacity for never giving up and also because he is willing to go great lengths to help a friend in need. She respected him for being determined and not giving up. Even though his methods got lecherous, she drew on his courage to help herself get stronger and braver.

She started to develop feelings for him after he helped her overcome her fear of Senjutsu because Issei told her he would stop her if she ever went out of control. After that, she began sitting nowhere else but on Issei's lap, and began seducing him like all the other girls in the harem. She often gets jealous like the others if another girl is displaying any sort of affection or acting intimate with him.

Her love kept growing and growing until it reached its climax in Volume 11 where she went into mating season and chose him as her partner, but was stopped by her sister, Kuroka. Later in the same volume, she proposed to Issei to be his bride, which Issei accepts under the condition that she grows bigger in both height and bust. She wants to be more than just a girlfriend to Issei because she chose him to be her soulmate. Her relationship with him is very serious, but will have to wait to develop more because her body is small and would be a danger to her to bear children at this point. When Issei died, she cried along with Ravel and was also happy to hear his spirit was alive.

Yuuto Kiba
Kiba is the Knight of the Gremory group and is the self-proclaimed best friend of Issei. Issei is extremely jealous of Kiba due to him getting all the girls' attention with his good looks and had strong feelings of animosity towards him in the beginning of the series. Eventually, Issei started to think of Kiba as a good friend after spending time together with him whilst training and talking about their futures together. They both want to become strong so they can protect the girls of the Gremory group. Issei and Kiba have a good friendship and are willing to protect each other from harm. When Issei died, Kiba felt sadness and anger but kept it in. He released his anger on Siegfried although losing but gained strength when one of Issei's Evil Pieces turned into Ascalon for him to use. Like the others, he gained hope when he found out Issei's spirit was alive.

Issei himself has occasionally expressed worries that Kiba might be interested in him, due to the latter not having a girlfriend despite his looks and some occasional dialog hinting towards it. Kiba also views Issei as a powerful rival and has several times stated he wants to be able to fight on his level or even defeat him.

During the side story of Volume 13, Issei fell ill with a unique ailment. During the time he was sick, he was nursed by all of the residents of his house (excluding his family) in actual nursing outfits bordering on lingerie. However, just before he fully recovered, Kiba appeared in front of him in a nurse's outfit. However, he had turned into a Bishoujo under the influence of the gender-swap ray created by Azazel. Kiba tripped and fell onto Issei right on top of the bed and their position turned out to be extremely embarassing. This may hint that Kiba, under the influence of a female's emotions, may turn out to have feelings for Issei.

Irina Shidou
Irina and Issei have been friends since childhood and reunited in Vol. 3, although Issei was surprised to see her because as kids he thought she was a boy. Issei likes her very much and has lecherous thoughts about her like the other girls. She had a crush on Issei since they were little but was shocked to see that he has become a Devil and a pervert but nevertheless, she still loved him. She wants to make love to Issei and have his children like Xenovia to apparently strengthen Heaven's forces out of influence of Xenovia's naivety. She loves Issei very much but is having trouble in the harem because if she thinks or does anything bad, she will "fall". However, it is suggested that she is willing to fall for Issei's sake.

Xenovia
Xenovia and Issei met in Volume 3 and did not care much for each other. Issei initially disliked her due to her calling Asia a witch and wanting to kill her, but after the events of Volume 3, she apologizes greatly and becomes a Devil after learning of God's death. She then decides that she wants to have strong children and chooses Issei to be her mate. She is completely oblivious to sexual situations due to her being raised in the Church, and tries to have sex anywhere with Issei, even going as far as to bring condoms to school so they could "practice".

Later on, she develops strong feelings for him because Issei helps her quite a bit, which she is fond of and therefore falls in love with him. She does not get jealous when girls are around him, often at times just letting it go, although when one of the girls tries to have sex with him, she becomes jealous and tries to take him away. Issei is willing to protect her just as much as the other girls, and loves the idea of having babies with her.

Gasper Vladi
When Gasper and Issei first met, Issei thought that he was another girl and was shocked after learning that he was a cross-dressing boy. Issei often cursed him for being a shut-in, although Issei and Gasper became great friends and Issei trains him as his junior. Issei's blood gives Gasper a boost in power, even making him able to hit his Sacred Gear's Balance Breaker for a short time. When Issei apparently died in Volume 11, he seemed to transform, becoming filled with rage at the Khaos Brigade for killing his friend and senpai, and proceeded to defeat Georg with his new power.

The two of them are a proper senpai-kouhai, and Issei has taught Gasper several things and also helps Gasper with his troubles. The two are on extremely good terms and are a strong team. Issei appears to also teach much of his perverted ideals to Gasper, which the latter seems to be innocent enough to admire, twice Gasper has even helped Issei to use his dress break by freezing their targets in place beforehand with his Sacred Gear.

Rossweisse
Rossweisse is the second Rook of Rias' peerage and a teacher at their school. She never had a boyfriend, and was constantly teased by Odin about it. At first she had no interest in Issei and found his predicament with his harem funny, often teasing him about it. In Volume 12, she starts to come around to Issei, seeing that he is a caring person and shows interest in him to the point of wanting Issei to have multiple dates with her because she likes him.

Ravel Phenex
Ravel and Issei met during the Rating Game between Rias and her brother Riser and didn't really care for each other. After he defeated Riser at the engagement party, she became infatuated with Issei and in Volume 5, she starts to develop feelings for Issei, albeit in a tsundere fashion. In Volume 10, she moves in with him and transfers to his school in order to spend more time with him. She has stated that she does not mind becoming one of his concubines as long as she is by his side, which shows that she truly loves him despite being a tsundere. Issei, however, remains oblivious to her feelings but was still willing to put his life on the line to protect her because Ravel's mother told him to take care of her.

Sona Sitri
Sona at first treated Issei like a regular servant, but as time went on she grew to admire him for his tenacity and courage. She respects him greatly for everything he has done, but she is also jealous as well because Issei solved many of Rias' problems for her which she, as her best friend could not do anything about it due to her position as a High-Class Devil. She considers him a great friend and suggested to Issei that he should call her by her first name, and told him to take care of Rias even though she's stubborn and has a great deal of pride. She has admiration and respect for him and for his accomplishments and everything he has done for Rias, and she also congratulated him on his promotion recommendation to Middle-Class Devil.

Genshirou Saji
Saji and Issei have a friendly rivalry going on because they are both Pawns, they both harbor feelings for their masters, and they both have Dragons sealed inside their Sacred Gears. At first they did not care for one another, but as time progresses they eventually became good friends, even stating that they are "War Buddies" in Volume 3 of the light novels,and have started training to become strong to face one another again. When Issei died, Saji showed expressions of anger and sadness due to him being killed and wanted to avenge Issei.

Tsubasa Yura
She congratulated Issei for his promotion recommendation to Middle-Class Devil and asked for his autograph, saying that Issei is the type of guy that she likes because he is always muddy after a fight, and admired Issei for his fight with Sairaorg Bael.

Raynare
Raynare was Issei's first girlfriend, in which she disguised herself as Yuuma Amano to trick and deceive Issei in order to kill him because he was deemed a "threat". She killed Issei with a light spear at the end of their date, and afterwards killed Asia by stealing her Sacred Gear. This caused Issei to hate Fallen Angels altogether. Issei later defeats Raynare and was nearly tricked (due to her becoming Yuuma once more) when she was trying to convince him to spare her life, but he sees through her ruse and allows Rias to kill her.

Although dead, Raynare left a permanent mark in Issei's heart, as explained in Volume 10 when Koneko, Asia, and Akeno try to "heal" Issei. She made Issei fear women after he planned his whole first date with Raynare, only to be killed and treated terribly by her. She also made him afraid to call girls by their first name (i.e. calling Rias "President (Buchou)" instead of her name), and also made him afraid of being disliked by other girls or rejected if he ever showed his feelings again. After being laughed at by Raynare in their final confrontation Issei also seemed to form a sort of mental block, making him oblivious to the attentions of the women around him. For example, before volume 10 he constantly assumes that Akeno and Rias's attention is because he is their 'cute kouhai'. The girls, however, eventually figure this out and Raynare's "curse" is lifted from Issei's heart. After this he is noticeably more perceptive of the girls attentions, though he is still oblivious at times.

Azazel
Issei, at first, hated Azazel because he was a Fallen Angel, but learned later on that he means well and has good intentions. Issei respects Azazel a lot, even calling him "Sensei" after Azazel tells him that he would teach Issei the secrets of the Sacred Gear and how to ensnare beautiful women. Azazel later became the Occult Research Club's advisor in Volume 4, and aided the Gremory team on how to better improve themselves as a team. He also helped out in progressing Issei and Kiba's Sacred Gears, as well as help Issei learn how to achieve Balance Breaker and control the Trianna. He also shows a great deal of concern for Issei after his death but is relieved to hear his spirit is alive.

Baraqiel
Baraqiel at first hated Issei because he misunderstood the meaning of Oppai Dragon as a Dragon who feeds off of breasts, instead of a Dragon who loves them, and as such believed that Issei wanted to eat the breasts of his estranged daughter, Akeno. However, since coming to understand the mistake and having been reconciled with his daughter because of Issei, Baraqiel has shown his approval and respect for him.

Michael
Issei sees Michael as a very powerful leader and respects him very much. Likewise, Michael has also shown a great liking towards Issei due to his kindness and power. In Volume 4, Michael gave Issei Ascalon as a symbol of peace between the Three Factions prior to the events of the Kuoh Treaty.

Gabriel
Issei views Gabriel as a beautiful woman and was desperate to hit her with his Dress Break in order to see her naked during the Sports Day between the Three Factions.

Sirzechs Lucifer
Sirzechs is Rias' older brother and met Issei during his duel against Riser at Riser's engagement party. He shows a great interest in Issei and considers him part of his family, even asking Issei to call him his big brother. He showed anger at Issei's death and, like the others, wanted to avenge him. He was also happy to hear his spirit was still alive. He has shown great faith in Issei's relationship with Rias as they progressed on. He later passed on his role of "taking pictures of Rias while she was sleeping" to Issei, though Rias was upset and said she didn't mind Issei doing it but heavily rejected Sirzechs with doing such things.

Serafall Leviathan
She has a minor rivalry between Oppai Dragon and her own magical girl television series, but is shown to get along well with Issei.

Ajuka Beelzebub
Appears to like Issei, even being willing to illegally modify his Evil Pieces so as to allow him to promote at any time. Whether this is more of an experiment on his part, a favor to Sirzechs, or for some other reason, is unknown.

Falbium Asmodeus
Falbium is the laziest among the four Satans to the point that he leaves everything to his servants much to Issei's dismay but he still helped in administering a trial for Issei and Rias in Volume 8 dressing as Satan Green.

Lord Gremory
Lord Gremory is Rias' father and meets Issei through her (although after the fight with Riser). He at first was disappointed at the fact Rias did not marry Riser to connect the families, but later accepted his daughter's content of loving Issei. He became fond of Issei and becomes good friends with Issei's parents and accepted him happily into his family, even wanting Issei to call him father. Like Sirzechs, he also shows great faith in Rias and Issei's relationship, although he often embarrasses the two (more often Rias). He also supports Issei's harem.

Venelana Gremory
Venelana is the mother of Rias. She, like her husband, was also very disappointed at the fact the the engagement between Riser and Rias broke off. She, however, became fond of Issei, with Issei having some lecherous thoughts of her because of how young she looks and how she bears a striking resemblance to Rias. She teaches Issei how to dance and eat fancily and become a proper gentleman so that he does not embarrass Rias at social events in the Underworld. She accepts her daughter's decision to love Issei and comes to like Issei, eventually accepting him into the family. She supports the idea of the harem and tells Issei to always protect the girls and keep them happy.

Grayfia Lucifuge
Grayfia is the wife of Sirzechs and Rias' sister-in-law. She first met Issei while retrieving Rias, who was in the middle of trying to make love with him. She was there after the Occult Club's defeat in the Rating Game against Riser, and helped Issei bring Rias back and stop the engagement. She shows great concern for Rias but accepts Issei as her love. Like the rest of the family, she is also fond of Issei. In Volume 12, she was one of the few to not even consider the possibility of his death, stating that she 'would not allow the person who will become her brother-in-law to perish with something like this [Shalba Beelzebub and Samael's curse]'. At the onsen in Izu it is revealed that she is very happy about Issei joining family and treats him as her little brother and washes his back, much to his surprise. She also demands to be called "Ane" (elder sister) by Issei— much like how Sirzechs wishes to be called "Oni" (elder brother).

Millicas Gremory
Like his father, Millicas likes and respects Issei calling him "Issei nii-sama". In fact, when Sirzechs ask Millicas on whether he likes Oppai Dragon or Satan Red more, Millicas chose Oppai Dragon much to the shock of his father.

Lady Phenex
She is the mother of Ruval, Ravel, and Riser. She met Issei in Volume 10, telling him to take care of Ravel, knowing that she is in love with him and was willing to be one of his concubines. She shows faith in Issei to please all of the girls and protect them.

Riser Phenex
Riser was the main antagonist in Volume 2. Issei disliked this man at first because he was stealing Rias away from the group, which Issei did not want. At the end of the Rating Game between Riser and Rias' peerages to determine whether Rias should wed Riser, Issei went against Riser but ran out of stamina and was beaten to near-death before being saved by Rias, who surrendered in order to prevent any further harm to him. He woke up two days later and went after her, interrupting the engagement party, and Sirzechs decided on a one-on-one battle. During that fight, Issei gave up his left arm to reach his Balance Breaker and ended up defeating Riser. Issei made him go into a state of depression due to the fact that he has never lost and also made him afraid of Dragons. Later on during the invasion of the Underworld, he overcomes his fear of Dragons due to Tannin's training and went out fighting and also tried to help Ravel deal with Issei's death. Issei didn't really hate him after he took back Rias. Riser is still jealous of Issei's relationship with Rias, and wants to fight him again.

Isabela
One of Riser's Rooks. After Issei defeated her in the Rating Game between their masters, Isabela started to respect Issei's strength.

Sairaorg Bael
Sairaorg is the cousin of Rias who met Issei when they were deciding Rating Game matches between the young Devils. He is known as the strongest young Devil. Wanting to fight each other from the beginning, they then sparred before their match, in which Issei found him to be extremely powerful and Sairaorg finding Issei to be interesting.

During the Rating Game match between Rias and Sairaorg's peerages, Issei and Sairaorg went head-to-head in a fist-fight match. Later, Issei found that Regulus, his Pawn, was a Sacred Gear which he formed with and activated Balance Breaker with. The fight continued and ended with Sairaorg being knocked out while still standing. After the match, the two became good friends and promised to get stronger to fight each other once again later on. When Issei apparently died, he came and encouraged Rias to get up from her depression. He believed that he was not dead due to the fact that he had not had sex with the women he loves.

Diodora Astaroth
Issei hated Diodora from the start as he was trying to take Asia away. Diodora, in turn, looked down on Issei, referring him as a "filthy Dragon" and stated that being touched by him made feel sick. Issei's hatred for Diodora grew to its peak when he learned that the noble set up Asia on purpose on the day she healed him, which resulted in her excommunication from the Church and labeled a heretic, just so he could add her to his "collection".

Vali Lucifer
Vali is the holder of the Divine Dividing Longinus and Issei's rival. When they first met, Vali was on another level compared to Issei, which made Issei devoted to becoming more powerful. During the signing of the peace treaty between the three factions, he went against everyone and formed a team in the Khaos Brigade. This made Issei hate him and after which they fought with Issei in Balance Breaker mode due to Azazel's bracelet. Issei won the fight but Vali was teleported away. Later on, however, the two joined forces to defeat Loki, and after that, began cooperating. Even later into the series, the two started to become friends, although still in a rivalry. They promised to fight each other someday and to become even stronger.

Kuroka
Kuroka is the elder sister of Koneko. She met Issei in Volume 5 when she tried to take Koneko, with Issei and Rias stopping her. He fought her for Koneko and almost punched her in the face but stopped at the last moment, warning her that if she ever tried anything again, his fist wouldn't stop. Later on, Issei found that she loves her sister very much and found her to be very sexually appealing. During Koneko's mating season, she made matters a little worse by stimulating Koneko and Issei. Although she stopped her sister, she still began to seduce Issei because she wants his "genes" for strong babies, which she tried with Vali but he denied. Koneko vehemently protests by protecting Issei, saying that Issei is hers. In Vol. 11, Issei tries to protect Koneko but is unable to do so because of the injuries sustained during his fight with Cao Cao. However, Kuroka protects her, after which he learns about her past while she is healing and tells Koneko she is a good person, although a "naughty cat".

Le Fay Pendragon
Le Fay is the witch of the Vali Team whom Issei meets in Volume 9, where it is revealed that she is a huge fan of his show, Breast Dragon Emperor Oppai Dragon (Oppai Dragon for short), wanting to shake hands with Issei and asking for an autograph upon meeting. It is unknown if her emotions towards him are any stronger. She later gives him advice on boosting his magic power as well as choosing a magician to form a contract with. She herself was considered a perfect candidate to be that magician by Ravel's statistics, but unfortunately she can't let her take up that position because of Le Fay's status as a terrorist of the Vali Team renders it impossible for her to become publically ascociated with Issei.

Cao Cao
Cao Cao and Issei start off with an initially hostile relationship due to the former being a leader in Khaos Brigade and for abducting Yakasa. Cao Cao also defeated Issei fairly easily during their insuing battle and caused him to awaken his Illegal Move Trident ability. Following their confrontation Issei did manage to rob Cao Cao of one eye, which would ultimately be replaced by an eye of Medusa. Issei's dislike of him is furthered when he attacks him and his friends later to take Orphis' power away form her. Cao Cao himself however seems to hold Issei in fairly high regard during their later confrontations, especially after Issei returns from the dead, which even manages to make Cao Cao believe he can only be a true monster. Issei's earlier wounding of Cao Cao's eye continued to be a factor even in their final battle, as Issei managed to use Samael's poison on his Medusa's eye and cause him near fatal levels of pain. Alongside Kiba, Sairaorg and Vali, Cao Cao is one of the few people who hold an intense rivalry with Issei so pronounced that he occasionally despairs at the notion that he's becomming more popular, specifically popular among men and strong fighters who interupt his peace.

Ddraig
Ddraig is the Dragon known as the Red Dragon Emperor that is inside Issei's Sacred Gear/Longinus, Boosted Gear, and has the ability to double his power as well as other abilities. He seems to hate Albion, the White Dragon Emperor, though the reason for it is unknown. He gets along with Issei very well, but later on when everyone starts calling him the Oppai Dragon, he becomes extremely depressed due to his credit being demolished little by little. Going so far as to require medicine and counseling for the depression. He has a great interest in Issei due to him never giving up and protecting the ones he loves. When he was with Issei when he died, he was devastated and told Ophis he was the greatest possessor of him, although he comes back along with Issei.

The two are nakama to the end, which was something Ddraig had never exprienced before. However, Ddraig expreriences extreme embarassment and heartburn because of Issei's lecherous thoughts and words to the point he requires medication and counseling.

Tannin
Tannin is the Dragon that Issei trained with in the Underworld. He was the one responsible for helping him become stronger and attain his Balance Breaker. Issei and Tannin have such a close relationship that Issei calls him "Old-man Tannin". The two are really good friends and have fought numerous battles with each other. He was, at one time, a Dragon King and knew Ddraig before he was sealed. When Issei died, he was sad along with many others but rejoiced when he came back.

Ophis
Ophis officially met Issei at his house when Azazel invited them over to negotiate. At first, he was afraid of her because he thought she would destroy them immediately. Although she has no intentions other than to defeat the Great Red and return to her birthplace in the Dimensional Gap. At first, she took a huge interest in Issei because of how Ddraig was and reacted with Issei and how his color had changed from red to crimson. In Volume 11, Issei became Ophis' first friend, and he invited her to live with him in the Hyoudou Residence. Ophis is also Issei's last friend (according to Ddraig) prior to his reincarnation as a humanoid Dragon (later Dragon/Devil hybrid). In Vol. 12, she plays a big role in reviving Issei with the Great Red's help, and now stays with Issei.

Ophis is similar to a child mimicking everything she sees, as she has often wanted do things normally done by the other loving members of the Gremory group to Hyoudou-kun. However, she is also oblivious to the standards of society and most emotion, as she would blaatantly lift her skirt up just to prove the fact she did not have underwear.

Great Red
The relationship between Issei and the Great Red is somewhat vague, as the Great Red rarely communicates with anyone and most of the communication between the two has been through Ddraig. However, the Great Red was willing to save Issei and Ophis when the pocket dimension they were in collapsed, hurling them into the Dimensional Gap. He also crafted a new body for Issei from his own flesh. This seems to indicate that the Great Red likes Issei, possibly because of Issei's powerful dream to become Harem King and the Ultimate Pawn.

Because Issei's present body has been made from the Great Red's, Issei can merge with his power with no effort.

Issei thinks of the Great Red as almost like a super-powerful delinquent because of his tendency to just fly around the Dimensional Gap and taking offense at being glared at. Issei is also embarrassed by the Great Red's apparent fondness of the Oppai Dragon theme song, a line of which is the only words directly exchanged between the two.

Issei's parents
Despite the fact that Issei constantly complains about his parents, Issei does love them deeply. In Volume 4 when Vali mentioned that he should try killing Issei's parents, Issei was so mad that he wanted to kill Vali on the spot.

His parents are like any normal parents, who are (somewhat) proud and very worried about their son. Issei's mother even went on about how she was worried that Matsuda and Motohama were a very bad lecherous influence on Issei.

Matsuda and Motohama
They are Issei's two closest human friends and fellow members of the Perverted Trio. The three will often get together and perform such activities as peeping and watching/reading porn. However, when push comes to shove, the two are completely willing to leave Issei to his own devices and receive their share of the punishment. The two have become very jealous of Issei's newfound popularity with the ladies.

Morisawa
Issei's first interaction started off rocky with Morisawa doubting Issei's abilities as a Devil and preferring Koneko over him. However, they soon bonded over their childhood love of "Dragon Ball" (Drag So-Ball in the Anime) and ended up establishing a strange albeit friendly relationship.

Mil-tan
Despite Issei's continual apprehensiveness around Mil-tan, he considers him to be a nice person and they appear to have a good relationship.

Aika Kiriyuu
Issei always complains about Kiriyuu that she always teaches/tells Asia erotic things. However, the two are on relatively good terms when not at odds.

Kiyome Abe
She met Issei when Rias needed to write a report about Youkai in Volume 8, but she didn't want to do it because she feared that she might lose her soul should she get involved with Devils. However, she agreed to do it if the Occult Research Club could prevail over her team in a tennis match, with the conditions being that if Rias lost, she would have to give up Issei temporarily. Unfortunately for her, she lost and had to write the report. Later on, she asked Issei to help her break an engagement that her father set up. Issei decided to help her in a tennis match against her father, and in the process of helping her, she fell in love with him.

Kunou
At first, she was under the impression that Issei kidnapped her mother and attacked him and his friends. After he saved her mother from the Hero Faction in Kyoto, Kunou developed a crush on Issei. She is also the young leader of the Youkai in Kyoto.