Kankichi serves as the younger brother of Moko, a central figure in the series. His full name fluctuates across adaptations, debuting as Kankichi Ina in the original manga before shifting to Kankichi Naniwa due to the first anime's influence. This name honors Tomoko Inao's father, acknowledging her collaborative role during development. Physically, Kankichi’s design transforms significantly. In the 1962-1965 Ribon manga serialization, he mirrors a youthful Matsuno sextuplet from Osomatsu-kun: a chubby second-grader with round features, "cheek beard" markings, and a single curly cowlick. He typically wears striped shirts with shorts or pants, or a blue sweater in cold weather. The 1968-1969 manga relaunch aligns him with the anime, adopting a wider face, freckles, and standard cowlicks instead of the curl—though reprints of older chapters occasionally retain his original face by mistake. By the 1988-1989 manga, his face widens further with rounder eyes, and he frequently sports sweaters featuring polygon patterns. Kankichi’s personality shifts drastically between iterations. Early portrayals depict a mischievous yet vulnerable child who fakes stomachaches to dodge schoolwork or conflicts. Cowardly against stronger figures, he endures frequent scolding or physical discipline from his sister and others. Despite these flaws, he upholds a moral core, exemplified when saving money to replace a younger boy’s bicycle after Chikako blackmails him over the damage. Later adaptations, especially 1980s manga, amplify his abrasiveness and temper; he routinely insults his sister as "kusobaba" and mocks Akko as "Baka-akko." This coarseness coexists with softer traits, most persistently his unshaken romantic affection for Chikako—even when she morphs into Chikako to mistreat him and deter his advances. His relationships further define him. With Moko, sibling conflict involves her scolding or hitting him for mischief, yet she shields him during genuine peril. He shares a close bond with Ganmo, the tofu shop owner’s son, their duo epitomizing youthful antics. Kankichi’s one-sided crush on Chikako fuels recurring plots, often complicated by her gossip. A notable crossover with Osomatsu-kun occurs when he meets the Matsuno sextuplets at the beach: Osomatsu steals his inner tube and intimidates him, prompting Akko to impersonate Kankichi and confront the brothers, leading to their apology and friendship. This encounter spotlights the shared "Star System" design philosophy, though later adaptations reduce their visual parallels. Key narratives underscore Kankichi’s moral complexity. One storyline sees him steal and break a boy’s bicycle, then earn redemption by working to replace it after Chikako’s blackmail. His habit of feigning illness backfires in escapades requiring Akko or Moko’s intervention. Across official media, his evolution mirrors the franchise’s tonal shifts—later versions heighten comedic rudeness while preserving glimmers of his early vulnerability.