Kousuke Endou/Relationships

Eiji Endou
Kousuke's father who works at the City Hall's Population Department. He tends to forget Kousuke's existence sometimes and worries about his younger son's future.

Misato Endou
Kousuke's mother who works at the City Hall's Municipal Tax Department. She tends to forget Kousuke's existence sometimes and worries about her younger son's future.

Sousuke Endou
Kousuke's older brother and a university student. He is jealous that his younger brother had managed to get a girlfriend and is on his way to even getting a harem while he has a history of not having a girlfriend equal to his age.

Manami Endou
Kousuke's younger sister, a middle school student, and a member of the Soul Sisters. She is sort of an otaku and is really excited at the aspect of his older brother getting a harem. However, Manami is in conflict over how to feel about Kousuke, as he works for Hajime.

Jugo Nagayama & Kentarou Nomura
They are Kousuke's oldest friends. Even though they had known Kousuke for years, they still can't perceive him and tends to forget about his existence even though they are near him.

Hajime Nagumo
Though Kousuke didn't used to have much interaction with him before the 'Summoning Incident', he was still affected by Hajime's supposed death in Great Orcus Labyrinth. After discovering that he was still alive, as well as learning about his journey and how he overcame all the odds, Kousuke started to have respect towards him, especially after Hajime helped him rescue his friends who were ambushed in the Great Orcus Labyrinth. Like most of his classmates who are terrified of Hajime, Kousuke takes his warning about killing anyone that stands in his way seriously, as he doesn't want to die by Hajime's hands, even after he murdered Daisuke Hiyama.

Later in the After Story, after the climactic battle, and Kousuke meets Lana, he went on to ask her out repeatedly. After countless attempts, Lana gave him the condition of clearing a Great Labyrinth and landing one hit on their boss, a.k.a. Hajime, before she would consider going out with him. Kousuke managed to achieve both of them, and Hajime has since then had respect for him. After the students return back to Japan, Kousuke becomes the only member of the Returnee's group who stays active and does various tasks for and with Hajime in order to protect and manage the safety of everyone close to them. Because of Lana's nature of wanting to gather seven wives for Kousuke and the fact that the "Abyss Lord" powers of Kousuke turned him into a, Hajime started to have a really close relationship with Kousuke and even considers him as a 'bosom friend'. Hajime also starts to egg Lana on her quest for a harem for Kousuke. This has resulted in many complicated situations for Kousuke as a result.

Despite being Hajime's right-hand man, there were times when Kousuke wouldn't hesitate to get back at him for being the victim of his antics. Putting aside on how Hajime suggested Lana for Kousuke to have more than one wife, Kousuke prevented Hajime from escaping Kouki's summoning with his clones and explained to Yue and the others after the return the real reason why it took them three extra days to return, in which Hajime told Kousuke to keep a secret.

Meld Loggins
The captain of the knight order was like a big brother to Kousuke and the other students. Meld was the person Kousuke respected the most in Tortus. Following Meld's death, Kousuke fell into a state of depression. He kept blaming himself for what had happened due to having been the last person to see him alive, as well as not noticing the changes in Meld's behavior during their encounter.

Allen Parker
Initially, the two of them were enemies and fought each other, but now they get along well together. This is evident when both of them were addressed by Myu without honorifics.

Lana Haulia
Kousuke's fiancée. She is one of the few people who manages to perceive Kousuke even after he uses all of his skills to hide his presence. This causes Kousuke to fall in love with her during the climactic battle. At first, he is rejected successively, but after seeing his determination, in order to hide her shyness, she presents him with a condition that if he can clear a Great Labyrinth and manage to at least put a scratch on Hajime, she will consider going out with him, which he eventually succeeds in doing. Witnessing Kousuke strength, willpower and love for her that allowed him to overcome both of her extremely difficult conditions, Lana fell in love with Kousuke and happily accepted him. As well, Kousuke gets elected as the next clan leader for the Haulia tribe after all the members witness his duel with Hajime. Because of his future position, Lana has adamantly decided to create a harem of seven wives for Kousuke and is looking around the world to find them. She also considers herself as the reason who created Kousuke's "Abyssgate" persona.

Emily Grant
Emily falls in love with Kousuke after going through much trouble involving a special drug she created. She entered Kousuke's harem by Lana despite the fact he didn’t want her to. He does accept her as one of his lovers and has one of his clones living with Emily and her family.

Vanessa Paradis
An agent from Britain's security bureau responsible for Emily's safety. She becomes infatuated with Kousuke after witnessing his abilities and "Abyssgate" persona. She enters his harem by Lana and declares herself his third wife. Their relationship is similar to Hajime and Tio's relationship, thus Kousuke doesn't punish Vanessa physically.

Claudia Barenberg
A saint from a secret organization "Omnibus" that is located in the Vatican City. She was hunted by a powerful Demon who wanted to use her body to aid in his rebirth. After the Demon was defeated, she confessed her feelings to Kousuke much to the shock of Emily. She is one of the few people to be able to perceive Kousuke at all times, which made Kousuke extremely happy he saved her.

Yaya no Hidzuki
Hidzuki is absolutely infatuated with Kousuke after he defeats her in combat while she is in a feral state in the Fairy World. After reuniting with Kousuke on Earth, Hidzuki wishes to be forever bounded to him. However, because of her status as an Oni, this translates to her wishing to eat him at some point. Kousuke vows to fight her with all his being if ever she tries to eat him, to which Hidzuki decides to be supportive to him after seeing the bonds forged between him and his other fiancées.

Hinata Fujiwara
Hinata develops an admiration towards Kousuke after her saves her life. This eventually turns into an attraction and wishes to be together with him. Kousuke is appreciative of Hinata's feelings, but refuses to reciprocate until she is older, to which she agrees. Hinata initially mistakes Kousuke as an Apparition due to him using his otherworldly abilities to protect her, much to his dismay that she doesn't believe he's human.

Unknown
A Demon from the Demon Realm. He attempted to capture Claudia but failed when Kousuke stepped in. They fought against each other again with Claudia after the Demons from Hell tried to invade Earth.

Eri Nakamura
Eri and Endou were friends as they were part of the Hero Party, but when Eri betrayed the Hero Party, Endou was quick to notice Eri's betrayal and tried to hide in the shadows so as not to be found, but Eri was quick to find Endou. After Eri found him, she tried to kill him, but Endou ran away so he wouldn't be killed and went to a safe place where Eri couldn't find him. When Endou joined the Haulia Tribe, Eri tried to kill him again, but was stopped by the Haulia Tribe members. After Eri's death, Endou learned of her death and took pity on her death, even though she betrayed the Heroes Party.

Kouki Amanogawa
Not much interaction was shown between them, except that they were both part of the "Hero Party". It had been implied that Kousuke was jealous of Kouki due to his immense popularity at both high school and in Tortus. Even so, he still cared for Kouki and the rest of his classmates.

Yue
She is Hajime's first wife and Kousuke's superior. She was present when Kousuke tried searching for help at the adventurer's guild to save his companions.

Shea Haulia
She is one of Hajime's wives. Not much interaction was shown between them except for the time when she and Hajime paid his clone a visit and their second meeting in the Demon Realm. He got annoyed when she asked him about his haircut. She was also present when Kousuke tried searching for help at the adventurer's guild to save his companions.

After hearing Hajime's story of his time in sci-fi world, Shea wished for herself to be summoned instead of Kousuke because then the threats posed on them will be too easy to handle. Shea also scolded Kousuke when he complained about having his stomach shot and cut by saying that a member of the Haulia tribe should not be bothered by that much.

Myu
Upon their first meeting, Kousuke yelled at Myu as he found her eating while explaining the hero party’s predicament frustrated him.

After they returned to Earth Myu stopped addressing him using honorifics because she got annoyed with getting beaten by the virtual version of Kousuke, much to his dismay.

Sharon Magdanese
The two of them initially were enemies, until after the Berserker incident. She was part of the group that agreed to have Kousuke be a representative of the Returnees.

Etemp and Netemp
The two of them worked with Kousuke in their battle against Mother. Similar to Hajime, Kousuke was somehow able to understand what the two of them were saying.