Touko Matsudaira, a first-year student at Lilian Girls' Academy and distant relative of Sachiko Ogasawara, wears corkscrew pigtails that inspired a senior to dub her "Mechanical Drill." Her sharp interactions with Yumi Fukuzawa—marked by brusque criticism—mask a blend of admiration for Sachiko and simmering insecurities. A standout member of the Drama Club, she channels her acting prowess to veil internal strife, from tensions with seniors to buried vulnerabilities like guilt over her adoptive family’s devotion and a dread of pity.

Orphaned as an infant in a car accident that claimed her biological parents, Touko was adopted by the Matsudaira family after no relatives stepped forward. A later registry search uncovered her biological mother’s past as a Lillian alumna and Drama Club member, while her adoptive mother—another Lillian graduate—mirrored the same coiled hairstyle, weaving threads of legacy into Touko’s identity.

Struggling with self-worth and an inability to reciprocate her family’s kindness, she deflects closeness, rebuffing Yumi’s offer to become her petite sœur as condescension. A turning point arrives during a candid outing with Yumi, where Touko unveils her orphaned past and tours Matsudaira Hospital, declaring her intent to manage it someday. This vulnerability lets her confront lingering guilt, culminating in accepting Yumi’s rosary—a testament to her emotional thaw.

Her evolution from guarded defiance to measured openness unfolds through interactions like those with Noriko Nijou, revealing gradual softening. By embracing Yumi’s mentorship, she steps into her future role as Rosa Chinensis en bouton, her journey reflecting the reconciliation of dual identities: orphan and heir, adoptee and legacy-bearer, navigating self-forgiveness amid entangled familial bonds.