Yoshino Koiwai

Born into a lineage sworn to serve the Adagaki household across generations, Yoshino walks beside Aki both as her loyal handmaiden and as a fellow student. Beneath her carefully maintained facade of clumsiness lies a razor-sharp intellect and a calculating mind—qualities that earned her the title of 'Master' from Masamune himself. Yet behind her composed exterior lies a burden she cannot shed: a childhood act of deception in which she impersonated Aki and unknowingly wounded Masamune. Driven by that lingering remorse, she covertly supports his scheme for revenge, hoping to atone for her past while quietly steering Aki toward her own growth.