Azuki Tomonaga, the 16-year-old eldest sibling of the Tomonaga family, shoulders household responsibilities and cares for her younger brother Yuuta and sister Kurumi while her archaeologist parents remain absent due to fieldwork. Balancing domestic duties with the challenges of adolescence, her limited culinary skills contrast her unwavering dedication to nurturing her siblings. Kind-hearted and perceptive, she extends emotional support beyond her family, offering solace to members of the Brave Police—notably aiding Shadowmaru in processing grief over his brother Kagerou’s death.

A quiet subplot reveals her affection for neighbor Masaya Kashiwazaki, whom she met at age 14. Supplementary materials note her passion for cake design, reflecting her creative domesticity. When her parents briefly return from an expedition, their reunion disrupts family dynamics, alienating Deckerd. Her father’s accidental introduction of a statue housing a destructive moth larvae triggers a citywide threat; Azuki aids containment efforts and later shares remorse with her father over the creature’s fate. The crisis unites the family in searching for the missing Deckerd, culminating in her father’s declaration of the robot as family.

Azuki’s narrative consistently underscores her empathetic bridge-building between humans and sentient robots, reinforcing emotional bonds without seeking prominence. Her stabilizing influence persists across media, maintaining her role as an anchor within familial and communal ties.