Marugoshi teaches at the school featured throughout the Harenchi Gakuen franchise. In the original manga, he frequently acts as an antagonistic faculty member. He confronts students while wielding a katana, but his attacks often lead to comedic humiliation when the removal of his apron exposes his genitalia, causing him to flee in embarrassment. Later, he enforces school rules, punishing students for eating during class, but falls victim to retaliatory pranks involving laxatives. This results in public exposure during an attempt to use a malfunctioning toilet.

In the sequel series Heisei Harenchi Gakuen, Marugoshi undergoes gender-confirmation surgery to remain a teacher at the girls' school. During a school trip, he appears at the beach in a bikini, interacts with students and colleagues, and demonstrates athletic prowess. Subsequently, he joins Principal Hige Godzilla and other teachers in a scheme using an astral projection machine, transforming them into ghosts to harass students. He participates in this supernatural harassment until students trap the ghost teachers.

Within the anime adaptation, Marugoshi features in an introductory sequence where he licks a video screen during an informational segment about the school, reinforcing his role in the faculty's unconventional behavior.