Mari Kudo appears as a secondary character in the *Escalation* arc, a three-episode storyline within an anthology series. A bright and earnest student at a Catholic girls’ academy, she befriends Rie Komatsuzaki, a newly transferred peer, becoming her first ally. Mari openly admires Rie, celebrating their bond with infectious warmth and proudly supporting Rie’s reassignment to room with senior student Naomi Hayakawa. Her deepening attachment to Rie draws scrutiny from Midori Omori and Naomi, who arrange Mari’s abduction after Rie’s piano performance. Confined to Naomi’s home, Mari and Rie are manipulated into intimate acts under the seniors’ watch. Despite the coercion, Mari persists in encouraging Rie, vowing to cherish their friendship beyond graduation. Mari’s arc ends with unspoken romantic longing for Rie, though she consciously upholds their connection above her personal desires. Her role remains limited to the *Escalation* episodes, with no elaboration on her history, family, or existence outside the academy’s walls.