Tōko Matsudaira, a first-year student at Lilian Girls’ Academy and distant cousin of Sachiko Ogasawara, navigates the school’s social tapestry as a drama club member distinguished by her corkscrew pigtails—a trait that earns her the moniker “Mechanical Drill” from Sei Satō. Her abrasive interactions with Yumi Fukuzawa, criticizing the latter’s perceived naivety, strain Yumi’s relationship with Sachiko. Yet this confrontational facade cloaks depths shaped by childhood tragedy: orphaned in a car accident that killed her parents, she was adopted by the Matsudairas after no biological relatives stepped forward. Overhearing hushed discussions and later consulting a registry, she uncovered her adoption and learned her biological mother attended Lilian alongside her adoptive mother—a revelation that drew her to the drama club her birth mother once joined, yet intensified her guilt over feeling unworthy of her adoptive family’s devotion.

Her acting skill becomes both armor and art, veiling struggles with club dynamics and emotional exposure. Though publicly dismissive of Yumi, she privately admires her kindness, yet recoils when Yumi offers the petite sœur bond, interpreting it as pity born from knowledge of her trauma. Rooted in a belief that relationships demand strict reciprocity (“give and take”), she fears accepting undeserved happiness.

A climactic outing with Yumi fractures these defenses. Amidst confessions of her orphaned past and the intertwined histories of her mothers, Yumi’s unwavering support compels Tōko to accept the rosary, embracing her role as Rosa Chinensis en bouton. This act marks her shift from brittle pride to self-acceptance, reconciling internal fractures.

Interactions with Sachiko oscillate between familial reverence and unspoken complexity, while her friction with Yumi catalyzes mutual growth—Yumi’s empathy tempering Tōko’s edges, and Tōko’s challenges sharpening Yumi’s resolve. Within Lilian’s tradition-steeped halls, her journey traces the weight of legacy, the shadows of concealed trauma, and the fragile negotiation between inherited identity and self-defined worth.