Rumi Tsurumi  

, 鶴見 留美

Rumi is a school student who faces bullying from her classmates. Hayato initially tried to address the issue by talking to Rumi in front of others, but this attracted more negative attention. After discussing the situation, Hachiman and his group decided that destroying trust between peers was necessary. They had Hayato and Kakeru act as bullies during a treasure hunt, exposing their selfish nature to each other. This prevented further organized teasing on Rumi. However, this approach may have left her with few friends after the incident.