The Red Dragon Emperor's Awakening[]
Gasper was briefly mentioned in Volume 1 by Rias who claims that he is in a different place, following a different order.
Birth of the Breast Dragon Emperor[]
Gasper being chased by Xenovia
Gasper first appears in Volume 4, after Rias was given permission to unseal him (much to his dismay). He then trains with Issei, Xenovia, and Koneko on how to control his Sacred Gear and with Azazel's advice and Saji's help, improve considerably. During the attack by Khaos Brigade on the leaders of the Three Factions, Gasper was captured and used against his will before being saved by Issei and Rias with Issei using his blood to allow Gasper to control his power as the two of them overpower the female Magicians.
In Volume 5 he accompanies Rias back in the Underworld for the Young Devils Gathering. During the Rating Game between Rias and Sona Sitri, Gasper was the first to be defeated after the Sitri Group, tricked Gasper (who was doing reconnaissance by turning into several bats) into gathering all of his bats together in one place, then used garlic on him.
In Volume 6, during Rias and Diodora's scheduled Rating Game, the match was interfered by the sudden appearance of the Khaos Brigade and the revelation of Diodora's alliance, the Gremory group facing Diodora's peerage along the way. He supported Issei and Koneko while they fight against Diodora's pawns who are promoted to Queen. He was last seen, with the other members, cheering Issei and Asia on their three-legged race.
In Volume 7, Gasper and his club were in a big hall located at the basement of the Hyoudou residence as Azazel showed them a tokusatsu of the Oppai Dragon show based off of Issei that's currently popular with kids. The next day after school, he and his friends fended off the Sacred Gear users and anti-monsters sent by the Hero Faction of the Khaos Brigade. On the following day, Gasper tagged along with Rias, Asia, and Yuuto to spy on Issei and Akeno's date while wearing a paper bag on his head, but soon lost them when Issei and Akeno escaped. The Occult Research Club was then asked to serve as Odin's bodyguard as they are attacked by the Norse Evil God Loki and Loki's son, Fenrir. The Occult Research Club, along with Baraqiel, Rossweisse, and Saji, later teamed up with the Vali Team to fight their final battle against Loki and Fenrir.
In Volume 9, when the second years of their club went on the school trip to Kyoto, Gasper assisted the rest with issues at the Gremory territory. After everyone's returned from the Kyoto, Rias, Akeno and Koneko were angry at them for not informing the rest about the incident they faced against the Hero Faction while Gasper was attempting to calm them down.
The Heroic Oppai Dragon[]
Gasper snaps after Georg told him about Issei's "death"
In Volume 10, when Ravel had transferred to his class she got into a dispute with Koneko, he hid behind Issei in fear. The Gremory group and Sairaorg's team with later have a press conference before their match. Back home at the club room, all the members expressed their disappointment in Issei for not noticing Rias feelings which greatly hurt her.
Gasper and Xenovia faced off against Misteeta Sabnock and Ladora Buné during the Rating Game between their masters. When Xenovia's ability to hold Durandal was sealed, Gasper sacrificed himself to buy time and allow the curse to deactivate so Xenovia can defeat them. Back at school, the Occult Research Club decorated their club room nto a haunted house for the school festival where he dressed as Dracula which all the girls found adorable. He and the rest of the Occult Research Club members were later seen peeping at Issei who confessed his love to Rias, congratulating Issei who successfully became Rias' boyfriend.
In Volume 11, Gasper goes to the Grigori headquarters to increase his powers.
He returns in Volume 12, disappointed that he gained nothing until he heard about Issei's death from Georg, causing Gasper to undergo a change where he can create an enormous amount of darkness that devours everything (even the mist created by Dimension Lost), which allowed him to defeat the latter.
The Legend of Oppai Dragon and his Lively Companions[]
In Volume 14, Gasper receives an order from the Vampire faction to return back home during the negotiation between the Carmilla Faction and the Three Great Powers. Gasper was also shocked to learn that his childhood friend, Valerie Tepes, is now a Longinus possessor. He was later kidnapped by the Khaos Brigade and a group of Stray Magicians after they used a fellow first-year student as a hostage.
In Volume 16, Gasper returns to his birthplace to meet up with Rias and Yuuto who were confined in the Tepes Castle. He was then reunited with his childhood friend, Valerie, who became the new "King" of the Tepes Clan, but was greatly saddened to see her mentally broken due to overusing the Longinus, Sephiroth Graal, caused by Marius Tepes. After a tea party with Valerie, Marius appeared and agreed to Gasper's request to "free" Valerie. Gasper later learned the truth to Marius' true purpose and becomes determined to save Valerie. Upon reaching the lowest level of the basement, Gasper was shocked and despaired to see Marius having extracted the Longinus from Valerie as he shares one last conversation before Valerie's "death". Angered and disgusted by Marius and the Vampires that made use of Valerie, Gasper's hidden power awakens as he killed Marius and the Vampires that supported him. When the mass-produced Evil Dragons start attacking, Gasper used his darkness to cover the entire town, devouring the mass-produced Evil Dragons before going to assist Issei who was fighting Euclid Lucifuge. Gasper then attempted to attack Rizevim who gives out a retreat order but to no avail due to Rizevim's ability. After Rizevim and his team left, Gasper carried Valerie with him and had one last conversation with his father. After their return from Romania, Gasper participated in the meeting formation of D×D.
In Volume 17, Gasper and the Occult Research Club went to the Underworld and participated in the experience day for the school Sona Sitri built located at Auros in the Agares territory. While doing the respective activities assigned to them, Qlippoth managed to surround both Auros and Agreas inside a barrier and announced their intent to attack after a certain period of time. Before the time was up, they reconfirmed their plan and Gasper ended up pairing with Sona Sitri, creating numerous beasts of darkness and sending them to wherever Sona commands.
In Volume 18, Gasper and the other Club members went to Heaven to discuss with Michael about the Christmas project that the alliance is working on. At the end of the meeting, Michael informed them about the deaths of Church officials and the presence of Evil Dragons found at the attacks. Later, Gasper assisted in protecting Heaven from Qlippoth attack, using his monstrous form to fight against a group of Grendel clones alongside Akeno, Yuuto, and Rossweisse.
In the Extra Life of DX.1, Gasper participated in his master's rating Game rematch against Riser Phenex. He teams up with Rosswiese and takes down three of Riser's Pawns, they wait at the replica of the main school building where they meet Issei and Asia being escorted by Mihae to her master, as Issei and Asia head to the roof, Gasper and Rosswiese face off against Mihae which the pair manage to win. The victory goes to the Gremory Team as Issei was able to defeat Riser.
Valerie awakes with Gasper by her side
In Volume 19, along with other members of D×D, Gasper took part in the battle against Church rebellions led by Vasco Strada and Ewald Cristaldi. He was part of the team that would battle against Vasco, they all had difficulty beating him until Xenovia was able to beat him with Durandal and Excalibur. They are ambushed by Walburga and Evil Dragons, however, they gain the upper hand when her Dragon army are immobilized by Rosswiese, they began their attack against Walburga who activated her Balance Breaker that contained half the soul of Yamata no Orochi, in the end, she was defeated and arrested. Before Vasco was also arrested, he gives them a piece of Sephiroth Graal that Rizevim stole, the piece was later formed into a necklace and place around Valerie's neck, Gasper is then relieved to see her awake from her coma. Gasper and his friends later heard the news about Ravel went missing during her brother and Diehauser's Rating Game.
In Volume 20, days after Ravel and Riser's disappearance since their Rating Game, Gasper along with Koneko worries about the disappearance of their friend till they receive news of Ravel's safety from Ajuka who is protecting them. Gasper then travels with Rias and his friends to Ajuka's place in order to retrieve Ravel. Over there, Gasper and his allies and told about Ajuka's secret creation; the King Pieces as well as the corruption engulfing the Rating Games. When Issei's parents are kidnapped, D×D infiltrated Qlippoth's hideout on the stolen city Agreas to save them, Gasper uses his Balor form when the Gremory Team battle against the Evil Dragon who took Issie's family; Niðhöggr. All their attacks prove to be ineffective as the Dragon was equipped with several Phoenix Tears vials until Crom Cruach comes in and starts mercilessly beating Niðhöggr.
In Volume 21, A week after Trihexa was unleashed upon the world, Gasper and his friends assembled with an army of variant races on an island in the coastal waters of Japan awaiting the arrival of Qlippoths army. During the battle, Gasper goes into beast form carrying Valerie whilst protecting her from any Evil Dragons approaching. After Apophis had moved away from Trihexa, Gasper and Valerie head towards above the beasts head to retrieve the Holy Grail to prevent them from resurrecting any more Evil Dragons.
In Volume 22, Gasper discussed with Koneko about becoming second-year high school students, with Gasper reassuring her. Gasper, Koneko along with Yuuto reveal they have decided how they will address Rias once she graduates and will discuss it later with Issei. He, Ravel and Koneko was later present when Ouryuu Nakiri whom the trio were already acquainted with, introduced himself to the others.
Afterwards on the following weekend, he attended a fishing trip with the ORC group, Issei's parents and the Vali Team on an inhabited island owned by someone related to them. Together in a group consisting of him, Kuroka, Koneko, Ravel and Valerie, were locating a fishing spot for them. The young lad was exited to be fishing for the first time while Valerie was cheering for him. Gasper and most of Issei's friends were present during the latter's graduation into being promoted into a High-Class Devil. Later on he and the rest eventually graduated into the following year, after the ceremony Kiba Koneko and Gasper now felt it time to start referring to Rias as "Oneechan", Akeno becomes a little jealous as she also wants to be refereed to that as well, though Kiba though assured her that in time they'll will do so. A little afterwards he witnessed Issei proposing to Rias along with the other ORC members.
Red Dragon Emperor of the Blazing Truth × White Dragon Emperor of the Morning Star: The True Dragon(s) of the Kuoh Academy[]
Gasper attended the opening ceremony of the Azazel Cup for the Rating Game World Tournament and witness Issei's grand entrance through Ryuuteimaru.
In Volume 23, following their teams continues victories over the tournament, on their next match they faced an Ultimate-Class Devil and his peerage. Gasper had turned into a monstrous black beast and released a darkness that engulfed the entire sea, causing all of the opponents’ attacks to be swallowed by the darkness and then several of them were dragged into the darkness. In the end, Rias' team had won when the Ultimate-Class Devil had to surrender the match. Gasper and the whole Gremory were later seen at the spectator room for related personnel watching Issei's Rating Game match against Dulio.
In Volume 24, Gasper and his friends payed a visit to the school pool to enjoy themselves. He panicked when Valerie had fainted due to heat exhaustion, Koneko helped move her into the room. Soon they heard that almost everyone's parents had arrived at the Hyoudou Residence, when Gasper and the rest made their way there, they learned that the reason for their meeting was to discuss plans for the wedding ceremony for each of Issei's fiances. Sometime later, Gasper, Koneko and Millarca assisted Ouryuu and Bennia with moving the trash for the Student Council when they were attacked by a group of Grim Reapers, Bennia and Ouryuu were able to escape in time and arrive with Issei and Ravel for help. Later on, everyone found out the reason for their assault was to capture Koneko, due to her late father having done research on artificially creating Super Devils.
When it came time for the Gremory Teams Rating Game match against Vali's Team, Gasper stood by Rias' side on rooftops where he used his ability to surveillance the other fights happening. The two of them prepared to face against Fenrir as their opponent, Gasper stood up full of confidence as he stated that he'll defeat any foe that dares oppose them as turns into his Dark Beast form. Together they fought with the huge wolf using their Power of Destruction and Dark Beasts respectively, but Fenrir evades all their attacks and was able to torn off one of his arms. While he may have regenerated it, Fenrir quickly knocked him to the ground, as the wolf then charges at Rias Gasper used his beast to guard her. Left with no other options, Rias and Gapser used their new combo technique; Forbidden Invade Balor the Princess, a form that turns Gasper into a suit of darkness that Rias wears. Fenrir fall back as it detected it a threat but was frozen in place until it broke free using its aura and advanced upon them, however Rias had submerged into her shadow and reemerged from another as she strikes at the wolf with her Power of Destruction which destroyed the entire building. She again used the time stopping ability to hold Fenrir and to also redirect her attack at him again, but escaped in time once more. Their fight continues with ease as whatever damage she took was immediately healed by Valerie, that is until Gogmagog came in and worked with Fenrir to destroyed the building Valerie was in, forcing her to retire. Both Gogmagog and Fenrir then set their sights on Rias while Vasco makes his way there and prepares to strike at one of them. However Rias had reached he limit as separating Gasper from her as she then instantly collapsed onto the rooftop, Gasper advised her to retire as even Vasco's attack may harm her, understanding her position, Rias reluctantly forfeits the match.
In Volume 25, Gasper got his Longinus certification because of his Forbidden Balor View according to Roygun Belphegor. He joined his team and Issei’s team in the smartphone game called Belzebut for their training held by Ajuka. During their break from training, Gasper recalled on how Issei was watching over him since they met and protected Valerie. Gasper and his team travels to Valhalla to cheer for Issei and his team in their match. Gasper and his team celebrated at the Hyoudou Residence for passing the preliminaries along with rival teams.
Gasper reappeared in True Volume 1, arriving at the park where Issei was attacked by the unknown devils and transported them to the Underworld and began to discuss about them in the Hyoudou Residence. Gasper and the group arrived at the town where the devils were residing and some of them attempted to attack Gasper but he transformed into his shadow form that causes some fear in them. Like the others, Gasper became shocked to see Issei, Ddraig, and Bova in pain after a purple-haired girl started to sing until she was stopped by Rossweisse’s hypnosis magic power to put her to sleep. In the Hyoudou Residence, Gasper and the others became astonished to learn from Ajuka that the girl is Ingvild Leviathan, a descendant of the original Leviathan and a half-human Longinus user. After Ingvild woke up, Gasper and the group took to the beach on a unpopulated island with Rossweisse placing a barrier, Gasper was laying on the parasol because of the heat until they were interrupted by the arrival of the goddess Nyx. After reporting to Ajuka about Nyx’s actions and gaining the approval from Apollon, Gasper and the group headed to Nyx’s location and help fight off the devils that was summoned by the goddess by transforming into his beast of darkness form.
After Nyx was defeated, Gasper and his team traveled to the Agares territory for the tournament announcing the next matches and learned they will be facing Issei and his team in the first match.
In True Volume 2, Gasper and his team and Issei’s team watched the match between the two Hindu gods Indra and Mahabali, with the former winning the match after striking his lightning on Mahabali. He appeared later at the Oppai Dragon Stadium with his team for their match against Issei and his team and as the match started, Gasper went together with Rias, Yuuto, and Lint to plan an ambush and successfully took out Bova Tannin and Roygun Belphegor. Gasper remain by Rias’s side and they encountered Issei and Grayfia, decided to take on Grayfia as they chants to Forbidden Invade Balor the Princess and defeated her with demonic aura sphere and undo the transformation. Gasper and Rias was confronted by Issei, who had finished his with Yuuto and they began to transform into Forbidden Invade Balor the Princess form and they managed to negate Issei’s Pailingual because Gasper’s voice was within the transformation. When Issei’s tail part of his DxD armor latched onto Rias’s breast, Gasper became conflicted on separating from Rias or leaving her vulnerable for Issei finish her off and together they were defeated by Issei when he used Nyuutron Beam Cannon on them.
Gasper and his team celebrated Issei and his team’s victory at the Hyoudou Residence and he offered his assistance together with Valerie to the team if they need help, and later they watched the match between Team Babel Belial and Black Satan of Darkness Dragon King, with Diehauser emerging victorious. As Issei recalls about the second year students trip to Kyoto, Kunou offered Gasper and the other second year students to be their guidance.
In True Volume 3, Gasper attended the meeting of the Occult Research Club to decide a program for the autumn event and school festival after the school trip, with Gasper suggesting a play. On the day of the departure to Kyoto, Gasper and the other second year students were given farewell by Rias as they departed to Kyoto first and told them to enjoy the trip to their heart’s content.
After arriving to Kyoto, Koneko and the others meet up with the Issei and Rias, who inform them of the recent attack by Gressil and Sonneillon. After the discussion of a plan, Koneko and the second year students agreed to Rias’ order to protect Kyoto from a possible group separating from Erebus’ group. Gasper and his fellow second year students and teachers gathered in the uninhabited forest of Iwashimizu Shrine to wait for their enemies to appear and watch the conversation between Ouryuu and Ruruko until he rejected her offer of having him marry her, which she resulted her to complain to Koneko and Ravel. As Ruruko decided to search for a new boyfriend and when thought of Gasper, Koneko revealed to her that he has someone special to him as Ruruko complained that even he has a lover unlike her. As the artificial Devils finally appeared, as Gasper enveloped his body in darkness, changing into the beast of darkness and began attacking the artificial Devils as well as stopping their time, allowing Rossweisse to make a follow up attack.
In True Volume 4, Gasper and the group watched the match between Team White Dragon Emperor of the Morning Star and Team Journey to the West, which ended in Vali’s victory. After Issei’s group was attacked by Meredith Ordinton and the fake version of Ddraig, Gasper and the others arrived to assist them and managed to drive them away. Gasper arrived to the Hyoudou Residence after hearing the news of Issei lost his perversion and discussed the situation at the VIP room about the Longinus Alphecca Tyrant and the incident of Azazel’s UFO, which the incident that traumatized him. As the girls were testing Issei’s abilities, Gasper agreed with Elmenhilde that Issei’s power increased because of his sexual desires.
Gasper and the others arrived to England and they meet Magnus Rose, where they discuss about their strategy for their battle against Hades and Angra Mainyu. Gasper was tasked to be part of Rias’ team battle against Verrine and to avoid him from fighting Meredith as caution from being hit by the Holy Nail as he is a Longinus possessor. As Team DxD begin their operation, Gasper and his group and Le Fay’s group traveled to Meredith’s location and encountered Verrine at the mansion’s rooftop. Gasper began to chant with Rias to enter the Forbidden Invade Balor the Princess form to begin their battle and they ended being the victor of the fight. Gasper and the members of Team DxD arrived to assist Issei and Vali battle against Hades by weakening him for Issei and Vali to deal the final blow.
After the battle, Gasper was promoted to High-class Devil and was awarded his own Evil Pieces as he wanted to make a peerage to become a splendid Devil like Issei and Rias. Gasper and the members of Team DxD celebrated their victory at the garden of the Hyoudou Residence.