|“||I want to live this age with you, Ise.||”|
–Ingvild to Issei Hyoudou, upon becoming his Queen, True Volume 1, Life 5
Ingvild is a beautiful foreigner girl who appears in her late teens with a whimsical aura. She has long purple hair and has orange eyes.
She wears a white noble dress with cleavage that expose part of her big breasts, high slits and with sleeves. She also wears a black mini skirt.
After joining Issei’s peerage and becoming a student at Kuoh Academy, Ingvild now wears a female school uniform.
Ingvild is a kind and friendly person and enjoys singing as is shown when she sings at the fountain and for Issei and his group. Ingvild is also shown to love seeing the ocean and going on beaches with her friends. Unlike her fellow members of the Leviathan clan or any other descendants of the original Satans and akin to Vali, she doesn’t have an evil heart and doesn’t wish to rule the Underworld.
She quickly fell in love with Issei, as was revealed by her song in the battle against Nyx. She is even shown to be a little jealous of Issei's relationship with his harem such as when she and the other girls caught him with Akeno and Koneko, even thinking about acting like them despite considering it embarrassing.
She also appears to be quiet, shy and soft-hearted. She can be very observant, remembering what Meredith said to Issei before she attacked him when the other characters were talking about Issei condition.
Ingvild was born as a child to both a Human and a Devil from the Leviathan Clan and was living in the human world in the seaside city in Europe. At some point in the past, she ended up with the devil sleeping disease that made her enter into a deep sleep and her parents contacted with Leviathan nobles and sent her to the Underworld in an attempt to cure her.
Only the noble Devils that were a part of the previous Maou Leviathan faction knew about this information. Those noble Devils hid her, who was affected by the sleeping disease in their own territory, hiding it to the current government and even to Katerea Leviathan and the Old Satan supporters who joined the Khaos Brigade.
She continued to sleep for a hundred years. She awakened due to the manifestation of her Longinus, Nereid Kyrie.
After Ingvild and her Longinus were awakened, the Devils that hid her knew that they couldn’t keep her under their control and contacted with the current government and Grigori who took care of her and analyzed Ingvild's Longinus. After that, she was kidnapped by Nyx and put under mind control.
Red Dragon Emperor of the Blazing Truth × White Dragon Emperor of the Morning Star: The True Dragon(s) of the Kuoh Academy
Ingvild made her first appearance in True Volume 1, and was singing by the fountain which Issei was killed by Raynare. While biking to his house, Issei hears her singing and follows where it is coming from and as she stops singing, she realizes he’s the red dragon. They soon get attacked by the unidentified devils and, as a result, Ingvild stands behind Issei. After Issei defeated the unidentified devils, Ingvild was covered in blood from her dress to her face and used the handkerchief that Issei gave her to wipe the blood from her face. She looked at her hands covered in blood and calls it beautiful because it’s more of a crimson color and Issei’s armor is the same color as well. Ingvild then vanished without a trace after Issei called in Rias. She appears again after Issei and his friends were fighting the unidentified devils and she starts singing again, which causes Issei and Bova Tannin to partially kneel down in pain while affecting Ddraig as well. To stop her singing, Rossweisse wrapped her in a light blue aura, and used her hypnosis magic to control Ingvild as well as make her temporarily fall asleep.
Ingvild was sleeping in one of the rooms of the Hyoudou Residence and when she wakes up, Ravel sends Issei and Asia to talk to her. Ingvild then asked them to tell her if she is in Issei’s house which Issei confirmed and introduces himself and Asia. Ingvild then introduces herself but remembers her surname which the people in the hospital called her: Leviathan. Issei asked her why she was at the fountain which she answered the Sea and also said that she heard that everyone including her parents had already passed away. After having a brief conversation about how Ingvild wants to see the ocean, Asia suggests that everyone go to the beach. While at the beach, Ingvild is standing on the sand and looking at the ocean when Issei goes to talk to her. Issei tells her that he likes her singing and she thanks him for bringing her to the sea, and they converse where she reveals that she was born in the seaside city and loves the ocean. Issei tells her to go to the sea with him but she said she will be taken somewhere where her powers are going to be studied. Issei, however, tells her he will take her. Ingvild laughs at the fact that she became friends with the Oppai Dragon and Issei tells her to call him by his name since they are friends and invites her to eat with Rias and everyone else, but their conversation was interrupted by Nyx who appears from the sky with the intention of obtaining Ingvild in order to use her to control powerful dragons like Issei, Vali, Crom, Ophis, and Great Red. Nyx tells Ingvild her to sing which caused Issei to suffer pain again and she passes out due to the brainwashing technique caused by Nyx.
After being brought back to the Hyoudou Residence and being allowed to sleep for a while, Ingvild awoke and overheard Cao Cao's assessment that she would have to be sealed which could result in her being unable to awake again or be killed to prevent her power being misused. Realizing that her power could bring trouble to a lot of people, Ingvild stated that she was okay with being killed. This saddened Issei, who implored her to reconsider her choice as he stated that he would be sad if she were to die, which shocked her. After hearing Asia's plea, Ingvild reconsidered her choice and begged Issei to help her, as she did not wish to lose another friend, to which Issei responded by promising to defeat Nyx. She later was present when Issei and the rest of the Occult Research Club departed to defeat Nyx.
Ingvild was contacted by Issei through Akeno’s breast and asked her to sing for him. She became hesitant at first due to the pain she caused when she sang but agreed when Issei begged once again. Her song has been heard throughout the battlefield through by the breasts of the girls and powered up everyone. After Nyx was defeated, the brainwashing spell that was placed on Ingvild was removed by Rossweisse and she thanked everyone for they did for her. Issei’s queen piece began to glow and Ingvild also glowed, causing Issei to believe that he has found a suitable servant and asked if she can sing while being his servant which he agreed. Ingvild became Issei’s first servant and grew out eight wings due to her being the descendant of Leviathan, to which Issei agreed to help her put her wings away. After becoming Issei’s servant, Ingvild appeared at the Occult Research Club where Beelzebub informed the group that the Olympian gods Hypnos and Oneiros had offered to help treat Ingvild of her sleeping disease to which she agreed.
In True Volume 2, Ingvild appeared in Issei’s dream of him marrying his brides, with Ingvild among the first group and she became confused if she became a bride. In the morning, Ingvild went together with Issei, Ravel, Ouryuu, and Bova to do their morning marathon and she became used to running like she used to run back in her hometown but became harder for her because of her sleeping disease. After finishing the morning training, Ingvild was informed by Issei about her devil job and she was accompanied by him, due to her demonic power being too vast for the teleportation magic circle. Ingvild meets her first consumer Lavinia Reni, who thanks her for coming to help her with unpacking for the person who is moving into Kuoh Town, which turns out to be Vali Lucifer. She meets a another member of Slash/Dog Natsume Minagawa, who shook hands with and hopes to get along with her. After finishing her devil job, Ingvild received a white dragon plushie as gratitude from Vali and returned to the Hyoudou office with Issei.
In the night, Ingvild and the other girls catches Akeno and Koneko attempts to seduce Issei in Akeno’s erotic room and she wonders about hugging Issei naked but finds it embarrassing, and she and the others ended up sleeping with Issei. Ingvild joined Issei and his team to their training camp in the mountain for training, she began her training at the small river to master her water magic in a form of an eastern dragon, and trying to master her clan’s specialty Sea Serpent of The End and after putting back the water back into the river, Ingvild started to feel drowsy and took a break from her training. Ingvild and the two teams celebrated Issei and his team victory at the Hyoudou Residence and as Issei recalls the second-year students' trip, he tells Ingvild to fun at Kyoto, which she happily agrees.
In True Volume 3, Ingvild was half-asleep during the meeting of the Occult Research Club about doing a program they will be doing during the autumn event at Kuoh Academy. The group began talking about Kyoto, with Issei telling Ingvild to enjoy Kyoto and doesn’t need to worry when she is with Ravel and Koneko, which she happily agrees and tells Ravel and Koneko that she is under their care. After arriving to Kyoto by train, Ingvild and the second year students were at the Kyoto Sirzechs Hotel to meet up with Issei and Rias at the cafe to discuss the recent attack from Gressil and Sonneillon, but she was sleeping in the middle of the meeting until Issei woke her up to inform her about the battle coming and told her to wait in the hotel, but she insisted that she wants to participate because she believes it’s fate as she is one of his peerage. Ingvild and her fellow second year students and teachers gathered in the uninhabited forest of Iwashimizu Shrine to wait for their enemies to appear and was sleeping during the conversation and as the artificial devils appears, she eventually woke up to summon a water dragon and asked for Ravel for instructions, who is shocked at the sight of the water dragon. She unintentionally launched her water dragon at the artificial devils and became worried that she wasn’t supposed to attack them yet, while summoning another water dragon and later she protected Ouryuu from a artificial devil.
Powers & Abilities
Immense Demonic Power: As a Devil who is a descendant of the original Leviathan, Ingvild possesses an impressive amount of demonic power and has all the common skills and powers of one. Ingvild has the ability to teleport as she subconsciously teleported to the park in Kuoh Town. According to Rosswiesse's measures, the amount of aura Ingvild posses is equal to a Satan-class Devil or even higher. With her massive Demonic Power, she’s capable of summoning up to ten of thirty meters water dragons.
- Sea Serpent of the End (掉尾の海蛇龍 Tōbi no Umihebi Ryū) : As a descendant of the Leviathan Clan, Ingvild has the ability to control the sea and draw large amounts of water. At full power, she's capable of summoning floods, drown whole cities and create a snake-shaped Dragon made of water.
- Enhanced Strength and Defense: From the Rook trait of her Queen Piece, Ingvild has strength and durability enhancement, giving her enhanced strength and defense.
- Enhanced Speed: From the Knight trait of her Queen piece, Ingvild has speed enhancement, increasing her speed.
- Magic Expert: Her demonic power is enhanced due to the Bishop trait of her Queen Piece. Rossweisse describes Ingvild as a genius as she's managed to show knowledge with elemental magic.
Stealth Expert: Ingvild is shown to disappear without leaving a single trace, as Issei didn’t felt her presence leave.
Flight: Being a half-Devil, Ingvild can fly using her 8 wings.
Nereid Kyrie (果てしない緑の海の詩, Nereisu Kirie): A High-tier Longinus with the ability to manipulate Dragons and the Sea. Currently, Ingvild's power to control Dragons is stronger while her power to control the sea is improving.
It can be used to enslave Dragons to the possessor's will as well as weakening them or strengthening them. It is shown to be powerful enough to dispel the armor of Issei Hyoudou who was wearing his Crimson Armor, with Ddraig stating that it could potentially even affect Issei in his Diabolos Dragon God armor. Ajuka Beelzebub stated that the power of this Longinus could potentially control the Dragon Gods (Great Red and Ophis).
It is stated that the power to control the sea could potentially allow the user to control the entire ocean to sink a urban area and potentially an entire country. According to Rias Gremory, the Longinus could potentially be turned into a Sub-Species which can also control lakes as well.
As a High-tier Longinus, it has the potential to destroy the world.
- Breast Song Reinforcement: By using Issei's Diabolos Dragon God as a conduit, Ingvild can empower Issei and his allies who are present. The song can be heard through the breasts of women as the area is bathed in lavender light particles.
- Ingvild is named after the famous Norwegian actress with the same first name. 
- The name Ingvild is a combination of "dedicated to the god Yngvi" or "dedicated to the ancestors", with "battle".
- Ingvild and Asia are the only characters to be named after two celebrities.
- Ingvild is the second descendant of the original Satans to be a devil/human hybrid, with the first being Vali Lucifer. They also share other similarities with each other.
- Ingvild and Vali both wield Longinus that is related to dragons: Nereid Kyrie and Divine Dividing.
- Ingvild and Vali are the last two survivors among the other descendants of the Four Great Satans.
- Ingvild and Vali are so far the only descendants who are not pure-blooded Devils.
- Unlike their fellow descendants of the original Satans, both of them don’t have an evil heart and don’t wish to rule the Underworld.
- After the defeat of the Alliance of Hell, Ingvild is considered as a potential candidate for the new Satans, under the title of Leviathan due to her nature as a descendant of the True Leviathan's lineage.