Tsukasa Tomii serves as assistant to Ranko Takara, leader of Shin-Takarazuka Academy's Cosplay Club. A masterful seamstress, she possesses exceptional talent in designing and constructing costumes. However, Tsukasa exhibits profound shyness and reluctance toward competitive cosplay, often recoiling from stage performances due to her timid disposition. Ranko observes this apprehension and adopts a strict demeanor toward her, yet maintains genuine belief in Tsukasa's untapped potential. During a rainy encounter, Tsukasa collides with East Oizumi Academy's Chako Hasegawa, immediately identifying Chako's Utena Tenjou-inspired battle outfit and remarking she appears "dressed like a revolutionary girl." In the decisive sudden-death round of a cross-school cosplay tournament, Tsukasa confronts Chako—who embodies Princess Serenity—while costumed as Queen Serenity herself. Bolstered by encouragement from both Chako and Ranko, Tsukasa steadily overcomes her anxieties and cultivates the confidence to compete. She belongs to Shin-Takarazuka's team, reigning world champions in cosplay during the series' events.