Konishi

Konishi is a middle-school classmate of Ayumi Otosaka in class 1-C, introduced as a polite, shy girl before revealing a much darker side. She is infatuated with a classmate named Oikawa, and once he becomes visibly drawn to the newly transferred Ayumi, Konishi's jealousy curdles into something far more dangerous.

Beneath the demure exterior lies a genuinely sadistic streak — Konishi is willing to hurt someone she sees as a rival rather than simply lose gracefully. Her jealousy escalates to the point of confronting Ayumi with a box cutter, a moment that inadvertently triggers Ayumi's dormant ability and leads to the school building's collapse.

After Yuu Otosaka uses his time-leap ability to undo the incident, he confronts Konishi directly, bluffing her into backing off out of sheer fear — one of the few moments in the series where Yuu's manipulative streak is turned toward protecting someone else.