Okometsubu Fujiyama, nicknamed Fuumin, transfers to Wakame High School aiming to make one hundred friends. His ordinary appearance and reserved nature starkly contrast with the school's eccentric students, particularly Masaru Hananakajima. Recruited by the eccentric Masaru as a founding member of the newly formed Sexy Commando Club, he receives the nickname "Fuumin" and becomes unwillingly involved.

Fuumin acts as the primary narrator and audience surrogate, offering grounded reactions to the club's absurd activities. He consistently serves as the logical "tsukkomi" (straight man), countering Masaru's unpredictable "boke" (eccentric) antics with exasperation or reason. This establishes him as the voice of reason amidst the nonsensical martial arts pursuits.

Despite initial reluctance and his normal demeanor, Fuumin remains a dedicated club member, participating in their unconventional training and battles. He possesses no inherent martial prowess but contributes through observational skills and occasional mediation attempts. A consistent personal interest noted across sources is his affection for cats.

Prior history remains unexplored. Throughout the series, Fuumin maintains his core personality and role as the relatable perspective amidst the club's escalating antics and bizarre adversaries, including aliens and interdimensional beings. His character remains largely static across the manga, anime, and related media.