Kichinosuke is a miniature blue robot with an egg-shaped mechanical design, created by Jun Nonomiya as her first robotic companion. Visually categorized as a "cute machine," his behavior is frequently disruptive. His core function is serving as Jun's non-human sidekick, though he proves unreliable as a helper, often inadvertently causing complications for Jun, Zero, and others.

Personality-wise, Kichinosuke is consistently sarcastic and blunt, delivering snarky remarks toward Jun, Zero, and characters like the triplets, establishing him as a snarky non-human sidekick. Beneath this abrasive exterior, he demonstrates underlying loyalty and occasional kindness, fitting the "jerk with a heart of gold" archetype. Jun treats him like a younger brother, though he functionally operates more as a problematic companion than a reliable helper.

His role evolves with the introduction of Yukinojo, a second pink robot created by Jun as a female counterpart to Kichinosuke, forming a "pink girl, blue boy" dynamic. Initially intended for Zero, Yukinojo develops a bond with Kichinosuke, becoming his distaff counterpart. Throughout the series, Kichinosuke acts as an unintentional spanner in the works, particularly hindering Jun's attempts to pursue a relationship with Zero. He initially expresses disapproval of Zero, questioning Jun's attraction to him.

In the series' conclusion, Jun entrusts Kichinosuke to Zero as a parting gesture before Zero departs for England, signifying a shift in his primary relationship from Jun to Zero.