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. She is, however, conflicted that Kousuke works for Hajime, who is the Soul Sisters sworn enemy and bully.

Jugo Nagayama and Kentarou Nomura
They are Kousuke's friends. Even though they had known Kousuke for ages, 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 this 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 on, after the climactic battle, as 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 (Deceased)
The captain of the knight order and somewhat like a "big brother" to the students summoned, including Kousuke. The last time they met was when Kousuke tried to get tissue, which was due to one of the Soul Sister's mischief. That was just before Meld got assassinated, much to Kousuke's regret after finding out later on.

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 presences. This causes Kousuke to fall in love with her during 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 go out with him, which he eventually succeeds in doing. This causes her to accept Kousuke and because of his strength, Kousuke gets elected as the next clan leader for the Haulia. 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 doesn't want her to.

Vanessa Paradis
An agent from Britain's security bureau responsible for Emily's safety. She becomes infatuated with Kousuke and enters his harem by Lana and declares herself his third wife.

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.

Ehit (Deceased)
The Evil God who summoned him and his class to the other world Tortus.

Daisuke Hiyama (Deceased)
His former classmate who is a traitor. Endou was shown in fears when Hajime murdered Hiyama for his betrayal. Unlike Kouki, Endou doesn't condemned Hajime for this murder.

Eri Nakamura (Deceased)
His former classmate who is also a traitor who wanted to kill him and the rest of their classmates due to him and the other being in her way to make Kouki as her boyfriend.

Unknown (Deceased)
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.

MOTHER (A.I.) (Deceased)
The self-proclaimed "goddess" of the sci-fi world and the A.I. responsible for summoning Kousuke. Originally, she wanted him to fight against the people from other world, but it backfired due to his weird actions and thin presence, even bypassing security systems. It was also thanks to him, Mother lost control of the sacred tree due to her only focusing on Hajime, G10, and Noint/Netemp.

Hero Party (Disbanded)
He was initially part of this group as a scout until it got disbanded. He is now part of the returnees group as well as the most active member among them. This is due to him being the "right-hand man of Hajime.

Kouki Amanogawa
Not much interaction was shown between them, except that they were both part of the "Hero Party". It was hinted during his talk with Emily, that he was jealous of Kouki due to him being popular in class and the other world. He even felt happy when Kouki got beaten up by Shizuku.

Later on, he meets both him and Hajime in the sci-fi world. He was shocked by Kouki's change in personality that he initially thought that either Kouki switched minds with Hajime, or that Kouki got infected by Hajime. He also got hurt by him a few times, like getting cut in the stomach and getting punched.

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 there first meeting, Kousuke yelled at Myu as he found her eating frustrated him.

Later on in the After Story, 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.

G10
Not much interaction was shown between them, but they still worked together in defeating Mother in the sci-fi world.