Upon his death at Akatsuki's hands, Miu's father entrusted her to him. Miu is aware that Akatsuki killed her father, however, whether she intends to take revenge is at this stage unknown.
Miu lives in a small apartment with Akatsuki. She can be hostile toward Ousawa if he has done something to aggravate her, but generally treats him fairly. After spending some time with Akatsuki, Miu falls in love with him, but can't show it due to his perverted ways.
Akatsuki and Miu met Izumi on their first day of school, getting along well with both of them almost immediately. She has a slight attraction towards Akatsuki.
When she first met Akatsuki and Miu, she kept to herself as much as she possibly could. After a few instances of teasing by Akatsuki, however, he was able to convince her to open up. After that, she develops a small crush on him, but can't show it due to his perverted ways.
Kenya is a very cocky boy who, on the first day of Akatsuki and Miu's arrival at Babel, attempted to terrorize them. He got pummeled with little effort by Akatsuki who stated that he also likes to bully weaklings, especially weaklings who look down on other weaklings.
Since their first meeting, Akatsuki has had a very negative opinion of Hikami, as well as a sense of rivalry.
Although she dislikes his irresponsible actions and perverted habits, Haruka does respect Akatsuki for his strength and kindness to those in need. It is also hinted that she has developed a crush for him.