Mayumi Kenzo

Mayumi's relationship with her brother Riku is very chill and friendly at the beginning of the killing game. She tends to tease him about the little things, as any sister would. She has his back no matter what, and he has hers. When Riku's suspicion is brought up in the first trial, she defends him with her life. When the trial is over and the class is split on whether they can trust Riku or not she says that she believes in him, though he can have some crazy/shocking methods to his madness. Eventually, he convinces her that it would be best for her to distance herself from him in the killing game. Mayumi's frustrations can be seen with his decision. She thinks that he doesn't trust her or thinks she can help him clear his name.

Hikaru and Mayumi are very obviously into eachother. During the first trial they team up to watch the body and the two of them form a connection out of it, though the connection is a bit of a rivalry at first. After the shock of the first trial starts to fade, Mayumi and Hikaru can be found doing very competitive morning races, though they both say they're just "jogging." Through their competition, the two grow very close and form a romantic relationship. After Hikaru's death in the third trial, Mayumi teams up with Izumi Murakami in his investigation as the protagonist, becoming his sidekick for the chapter. More than anything, she wants to avenge Hikaru and help the killer get what they deserve.

Mayumi and Izumi don't interact at much first, but after the third class trial they become "jogging buddies." Since Hikaru was killed, Izumi wakes up early every day to jog with Mayumi, making sure she still has someone she can rely on. Mayumi beats Izumi at the race every day, but having someone to carry on the tradition her and Hikaru started helps her grieve and means everything to her. Mayumi often teases Izumi about his obvious crush on her brother.