Tsuyoshi Isobe, known by the nickname Kyasharin meaning "delicate bones" or "living bones," possesses an extremely emaciated, skeletal physique due to his addiction to vitamin supplements. This dependency weakens his health and strength, motivating him to join Wakame High School's Sexy Commando Club to build physical power and overcome his fragility. He briefly improved by replacing vitamins with proper nutrition and exercise, gaining some strength, but repeatedly relapses into supplement dependency. Each time he takes vitamins, he involuntarily exclaims "Okure-nisan," referencing a famously thin Japanese comedian. Before attending Wakame High, he demonstrated athletic prowess as his middle school baseball team's ace player. Within the Sexy Commando Club, he engages in their unconventional martial arts activities, which prioritize psychological tactics over physical combat. His presence contributes to the club's eccentric dynamics, while his personal goal remains conquering his physical limitations. The contrast between his past athleticism and current frail state underscores his ongoing struggle between potential and addiction.