Himeno Ruruna

A student who attends the same university as the protagonist, she is a gyaru who often moves form one circle to another. Uninhibited in sex, and has huge breasts that don't match with her petite body.

Although she is unaware of it, every circles that she joins are always bound to have a rift​, a Natural Circle Crusher​. By applying for a clinical trial that earns more than her Papa Katsu work, Ayumi takes an interest in her.​

At first, she was enthusiastic, but as the trial gradually became more extreme, she began to feel frightened.