Milk emerges as a wealthy 10-year-old struggling with invention, her skills placing her beneath the lowest official license tier. Assigned to a newly created "D-Level" category, she defiantly rebrands it "Deluxe-Level," masking her technical shortcomings with brash confidence. Her entitled demeanor and repeated failures clash with ambitious aspirations, mitigated only by reliance on Igor, a long-suffering interface robot functioning as both caretaker and unwilling accomplice to her impulsive schemes.

Five years later, she reemerges at 15 as a celebrity idol dominating Planet Sharaku’s entertainment sphere. Though traces of self-interest linger, she demonstrates growing awareness of others’ needs. Unreciprocated feelings for the protagonist simmer beneath her performative cheerfulness, sharpened by his emotional shift toward another.

Her dismissive rivalry with a fellow inventor gradually softens into ambiguous tolerance, culminating in a spontaneous farewell kiss that suggests unresolved tension beneath their guarded interactions. Despite remaining mechanically inept compared to peers, her celebrity status overshadows professional inadequacies.

Igor undergoes physical and functional upgrades across seasons, transitioning from household butler to career manager overseeing her idol ventures. Their relationship persists as a complex dance of dutiful support and exasperated endurance, mirroring her unpredictable whims yet reflecting subtle mutual dependence.