Kiyosumi/History

Background
Kiyosumi is a young high school student who sits behind a tortoise with retracted limbs known as Abu that has the word "hell" written on his shell, and wonders how he can make friends. She has never spoken to him and isn't the one to take action unless being told so. Later, a teacher informs Kiyosumi that there are students who smoke in the school. Since she is a member of the school's disciplinary committee, she asks her to inform her of any suspicious students and Kiyosumi agrees. Kiyosumi always does what is asked of her.

Shortly after, Kiyosumi meets the students who smoke, who when discovered are determined to continue smoking even when Kiyosumi tells them that she is only trying to do what she is told. At that moment, everyone is interrupted by Abu's presence. His limbs and neck are extended, and he says that they are in the place where he usually takes his naps. Terrified, the trio of students apologize and leave his "territory". Abu asks Kiyosumi if she is okay and she asks if it is really him, not recognizing him for having his limbs extended and showing his multiple tattoos. Abu states that it is him and retracts his body to show it. Kiyosumi asks if he is some kind of gangster. Abu denies it and alleges that everyone just moves away from him every time he stretches out a bit. Most of his tattoos are done by himself as Abu explains that he is trying to become a tattooist and has tattooed himself as practice. He reveals that he has always wanted to work on Kiyosumi dangerous horns. Kiyosumi remembers being told by doctors that if she let her horns grow too long, they would stab her in the head and Abu was the only one who noticed that she was approaching death day after day.

After school, Kiyosumi accompanies Abu to his tattoo studio. Abu claims that he didn't think Kiyosumi would be interested in something like this and dissuades her from getting a tattoo just to thank him for earlier. Kiyosumi alleges that's not it. Abu declares that she has nice horns and that he is grateful to be able to ink them, but asks if she had considered removing them. Kiyosumi claims that she is not sure and relates that at some point she began to feel like she wasn't able to do anything unless she was told to her, and maybe she has always wanted other animals to tell her what to do. She reveals that she has always wanted someone to save her life, but instead she continued approaching death for 17 years without anyone noticing, like an idiot. Abu begins to tattoo Kiyosumi's horns and tells her that everyone dies eventually, and everyone is too conceited to be worrying about her. Back when he first inked his shell, no one really cared, so he thought that living that way makes life much easier. After finishing the tattoo, which is flowers, Abu invites Kiyosumi to spend the night together to make them bloom. Kiyosumi and Abu spend the rest of the night walking around the city and having a good time.

A week later, Kiyosumi returns to school after a week off from her surgery to cut her horns. She is told by a classmate that without her horns her face looks much brighter now. Kiyosumi promised Abu that she would not tell anyone about the day they spent together, and he is probably congratulating her for making her first decision of her own volition because there were little flowers blooming on his "hell" shell.