Manga Debut: Chapter 57 (Ogress, Part 1)

Anime Debut: Episode 36 (Ogress)

A member of the school's field hockey team, she wasn't very good at the sport and asked for helpful tips from Himeko. Though not the sort of person who stood out, Arisa was well-liked, attentive and kind. At one point, Himeko believed that Arisa was being extorted by classmate Kyōko, but it turned out to be an act. Arisa had been paying Kyōko of her own volition in order to remain under the radar at school and to prevent any possibility of bullying - which she had suffered in primary school. As she was from a wealthy family, she felt that her only viable weapon was money. After tricking Himeko and luring her into a trap, Arisa stated that she had only befriended the former out of pity, thus leading Himeko to lose her composure and attack Kyōko's gang. Terrified, Arisa called her a monster and the two parted ways.

Several years later, when they are both in high school, Himeko and Arisa run into each other at a park near the middle school. Arisa revealed that she had been coming to the park every day since then in the hopes of seeing Himeko, in order to apologize. She gains closure when Himeko forgives her.