Otsu Tsurugaya serves as the Otogi Bank’s devoted maid, driven by an obsessive compulsion to repay every favor—a fixation rooted in a traumatic childhood incident where a neighbor died pushing her from an oncoming bus. This event left her terrified of unpaid debts, compelling her to meticulously reciprocate even minor gestures, often through extreme acts like laboring tirelessly at others’ homes until collapsing from exhaustion.

The Otogi Bank members, particularly Ryoshi Morino, actively counter her self-destructive cycle. When Otsu insists on repaying Ryoshi’s swift intervention during a baseball accident with relentless housekeeping, the group devises strategic scenarios to challenge her transactional worldview. Their efforts gradually lead her to confront the irrationality of her obsession, fostering acceptance of kindness without immediate repayment—a pivotal shift allowing her to embrace balanced relationships.

Otsu steadfastly dons maid attire, rejecting all other clothing as a symbol of her service-oriented identity. This choice aligns with her role and echoes the Japanese folktale *Tsuru no Ongaeshi* ("The Crane’s Return of a Favor"), reflecting themes of gratitude and reciprocity central to her character. Her growth unfolds through the Otogi Bank’s dedicated support, marking her journey from rigid obsession to understanding mutual trust.