Out of all the prison mates, Hajime trusts him the least, seeing the other three more as juveniles and not threatening, especially since their reasons for being in prison don't warrant any genuine harm or concern. He keeps a close eye on Jyugo who often annoys him with his escape attempts. Jyugo's opinion of him is not clear but he seems to enjoy teasing Hajime and aggravating him with his escape attempts. When Jyugo went into a moment of rage, Hajime did not hesitate to break several of his bones and send him into a coma to stop him.Yet afterwards, after knowing the reason why Jyugo kept extending his prison sentence, he claimed that he was empty and admits that he overestimated him, but afterwards he promised him that he would look for the scarred guard for him. It's shown he on slightly friendlier terms than before.
Like his friends, he enjoys teasing Hajime. Hajime tends to get annoyed with his antics like he does with the others but is usually able to prevent him from wanting to escape by showing him erotic magazines. However, their relationship turns sour after Hajime beats Jyugo, saying that Hajime was a worse monster for what he did and lectured him severely before kicking him out of the cell.
He enjoys teasing Hajime and challenging him to fights, which he always loses. Hajime gets annoyed by his antics but takes advantage of Rock's simplemindedness to keep him in line, usually baiting him with the lunch menu to keep him calm.
While the two have not much interaction, Hajime tends to get annoyed with him like he does with the other cell 13 inmates. However, he also refers to Nico as a good kid and the easiest of the cell mates to handle and seems to treat him slightly gentler than he does the other inmates due to being the youngest and least threatening. Nico acts friendly to Hajime though does tease him on occasion.
The two seem to get along and Seitarou is one of the few people Hajime has never been shown to get angry at. He gives Seitarou advice on how to handle the prisoners and advises him to have more confidence, while Seitarou looks up to Hajime as a role model and his superior.
Hitoshi is his younger brother whom he seems embarrassed of due to his crossdressing habits. Despite this, his younger brother cares greatly for him and often comes to visit him. When he is sick, Hitoshi is the one to care for him.
She has feelings for him though he is terrified of her, as her stares at him look like intense death glares from his perspective. He hides the fact that the cell 13 inmates often escape to keep his job. He is also frightened of her temper, shivering when she shows true anger. Despite this he does respect her power and abilities and sees her as a competent warden.