Inosuke Hashibira/Relationships

Tanjiro Kamado
Inosuke sees Tanjiro as a rival due to him enjoying competing with stronger opponents. Over the months that they spend together, Tanjiro has had a positive effect on Inosuke as, ever since meeting Tanjiro, Inosuke has been more open-minded about how others are strong, hence the Hashira. Inosuke also developed his ability to think and analyze the opponent's powers and skills. While Inosuke still thinks of Tanjiro as a rival in a sense, it is clear that he also cares for him, and the two have become close friends.

Zenitsu Agatsuma
In their first encounter, it was distinctly depicted that the two had vastly different personalities. Inosuke has a raging personality and is always ready for a fight whereas Zenitsu tends to be cowardly and prefers to avoid confrontation as when he was trying to protect Nezuko. Inosuke is constantly looked down upon by Zenitsu due to his lack of knowledge, even to the point where he is insulted for his stupidity. Despite this, the two manage to overcome their dislike for each other, and team up in order to defeat powerful Demons, such as when they encounter Daki in the Entertainment District.

Shinobu Kocho
Shinobu quickly learns to manipulate Inosuke in a similar fashion to Tanjiro, figuring out that she can convince him to undertake any task by second-guessing his ability to do so. Inosuke initially shows his usual abrasive and disrespectful attitude towards Shinobu, going so far as to threaten to rip her breasts off when he feels insulted by this second-guessing. However, it becomes clear that, after she cared for him in his injured state, Inosuke harbored affection for Shinobu, vowing to avenge her death when he learned that Doma absorbed her. Shinobu's sweet demeanor and use of a "pinky promise" with Inosuke inadvertently recalled deep subconscious memories of his mother. It is also noted that Shinobu is one of few people whose names Inosuke never gets wrong.

Kanao Tsuyuri
Inosuke has fairly minimal interaction with the detached Kanao during their training. Sometimes, his actions would make her see him as a weirdo e.g. - ceiling-clinging or dislocating all the joints in his arm and relocating them. However, the two later form a battle-forged bond while teaming up against Doma, who was responsible for the deaths of both of their loved ones. The pair make for an effective team in combat, and, with help from Shinobu's poison, they manage to slay one of the most powerful Demons in the series together, despite neither even being a Hashira. Afterward, though they exchange no dialogue, they share a moment to grieve the families they both lost to Doma. When they return to fight Muzan, they exchange some brief banter, and seem to work well together.

Kotoha Hashibira
Kotoha is Inosuke's mother. Kotoha deeply loved and cared for Inosuke as a baby. She promised to protect him and raise him happily, however that never happened when she found out Doma was eating his worshippers, resulting in her attempt to flee with baby Inosuke. She was cornered by a cliff when she made a rushed decision to throw Inosuke into the river in order to save him from Doma, and she had been killed and eaten. When Inosuke found out that Doma had killed his mother, he became enraged.

Aoi Kanzaki
They met each other, for the first time, at the Butterfly Mansion. At the beginning, he struggles to beat Aoi in all of the tasks due to not having a strong will. Later on, he is finally able to adapt and beat her. In comparison with Zenitsu and Tanjiro, he was more harsh against her. He was one of the slayers who volunteer in Aoi's place to go to the Entertainment District in a mission with Tengen. After the fight against Upper Moon 6, he's carried one more time to the Butterfly Mansion. Aoi is visibly sad about Inosuke's terrible condition, since he had poison through his body and she thought it was too late to stop the bleeding. Her tears were quickly dispelled however, as he drops off the ceiling. She starts to see him as a pain and start to argue with Inosuke again. At the Butterfly Mansion, he goes out of Tanjiro's room and heads to the kitchen to get some food. He tries to steal food behind Aoi's back, but she notices him. She hands him over a rounded tray of food that is made only for Inosuke and tells him that he can eat how much and whenever he wants from that tray. After this gesture, Inosuke visibly starts to see her in a good light. Eventually, she and Inosuke Hashibira marry and have a great-grandson named Aoba Hashibira.

Kyojuro Rengoku
Like Tanjiro and Zenitsu, Inosuke is immediately taken with the strong and magnanimous Kyojuro, looking up to him as a mentor and leader after they meet on the Infinity Train. After Kyojuro's death following his fight against Akaza, Tanjiro and Zenitsu despair, while Inosuke is the one to pick them up, correctly voicing that Kyojuro would want them to keep fighting and live great lives to honor his memory and sacrifice.

Gyomei Himejima
During Hashira training, Inosuke revels in the final phase of endurance testing under Gyomei, pushing himself to the point of falling unconscious while remaining on his feet under a freezing waterfall. Inosuke immediately admires Himejima for his incredible strength, identifying him as the strongest Hashira.

Doma
Inosuke only interacts with Doma for the duration of their battle, but rapidly develops a deeply personal hatred and desire for vengeance against him. This starts when he finds out Doma absorbed Shinobu, and takes on a whole new dimension when he finds out that Doma orphaned him and devoured his mother when Inosuke was an infant. For his part, Doma is intrigued by Inosuke's attitude and fighting style, and underestimates him entirely as an opponent, proving to be his downfall after both Inosuke and Kanao manage to slay him in battle.