Following his mother's death, fourteen-year-old Taro Hanaukyo inherits the vast Hanaukyo estate. His grandfather, Hokusai Hanaukyo, departs before Taro's arrival, leaving the boy master of the mansion and its staff of hundreds of maids. Taro exhibits a pronounced physical reaction to contact with women, often causing visible distress or collapse; Mariel, the head maid, remains the sole exception. This trait moderates in later storylines.

Physically short for his age, Taro's stature sometimes leads others to underestimate him. Yet he possesses a patient, persuasive, and quietly resilient nature. He rejects his grandfather's decadent lifestyle, demonstrating humility by treating the maids as equals and family. He replaces the opulent master bedroom with a simple futon in a corner, refusing the "bedwarmer" services of the triplets Lemon, Marron, and Melon. His leadership, emphasizing mutual respect and compassion, gradually earns the maids' genuine loyalty.

Taro develops a significant romantic attraction to Mariel, whose devotion borders on obsession. This intensifies when her origins are revealed: she is a genetically engineered "ideal maid" from "Project: Blue Silent Bell," her emotions suppressed by programming. Taro commits to helping her overcome these limitations, affirming his belief in her inherent personhood. His bonds with other key maids shape his growth: he communicates intuitively, possibly telepathically, with Cynthia, a mute girl possessing a split personality (Grace), supporting her during crises; he navigates Konoe Tsurugi's strict security by appealing to her underlying care for the household; and he tolerates Ryuuka Jihiou's aggressive marriage proposals—stemming from a rival family's mandate—recognizing her gradual maturity.

Hokusai Hanaukyo emerges as the primary antagonist, orchestrating conflicts from afar. Taro confronts these challenges by prioritizing the well-being of the mansion's community over dynastic expectations, solidifying his role as a compassionate and principled leader.