**Masa**, once an underling in Tatsu's yakuza gang, frequently assists with domestic tasks, often finding himself unintentionally embroiled in household chores and errands. His yakuza past colors his perspective, leading him to draw unexpected parallels between housewife duties and gang operations—viewing supermarket bargain hunts as high-stakes raids or neighborhood dues collection like gathering protection money.

He initially displays deep-seated respect and lingering intimidation toward Tatsu, maintaining formal speech and deferential behavior reflecting their former boss-subordinate dynamic. This relationship evolves as Masa adapts to civilian life, developing an unexpected appreciation for domestic work. His progression includes joining the PTA, aspiring to become a househusband after developing romantic feelings, and actively seeking Tatsu's guidance on household management techniques.

Masa's interactions often spark comedic misunderstandings, especially during collaborations like cooking duels or rap battles. His participation in a dessert competition against Tatsu and Torajiro showcases both his competitive streak and earnest approach to mundane tasks. His relationship with former yakuza rival Torajiro shifts from hostility to reluctant cooperation as they navigate post-gang livelihoods, including joint ventures like food truck operations.

Across adaptations, Masa serves as a foil to Tatsu, embodying the challenges of transitioning from criminal to civilian life while maintaining distinct comedic traits. His development involves expanding social connections beyond former yakuza circles, forming acquaintances with neighborhood residents and participating in community events like Halloween contests, where his competitive nature surfaces in non-violent contexts.