Abilities High Physical, High-Mid Academic, Mid Adaptability Riku Utomiya is one of the first-year students at Advanced Nurturing High School. He is a student of Class 1-C. Riku seems to have a calm personality, usually speaking casually to other people and his class seems to trust him in talking with the people in other classes. He does dislike people who use violence to get what they want and has no problem picking a fight with them if they go too far.

Spoiler

Riku is first introduced in Second Year Volume 1 walking up to Kiyotaka Ayanokoji with Sakurako Tsubaki asking Kiyotaka if he would partner up with Tsubaki because she had a C- in her OAA and was at risk of not finding a partner up until now. Kiyotaka refused their offer, saying he already had a potential partner in mind. Tsubaki and Riku accepted that and left after Riku gave his phone number to Kiyotaka if anything happened. He represented Class 1-C in a meeting between students of the four first-year classes, in order to negotiate regarding group formation for the upcoming uninhabited island test. He clashed with Hōsen during their session and accused him of being the cause of Class 1-C student Hatano's expulsion. When he grabbed Hōsen's wrist to stop him from lashing out at the others, Hōsen immediately knew that Riku was pretty strong.