Mono Shinobino is a student at Itan Private High School, instantly recognizable by his consistent ninja-themed attire. He pairs the standard school uniform with a black face mask, bandana featuring a metal plate, fingerless gloves, and scarf, creating a stereotypical ninja look. This mask has never been absent in the series proper, except during a single fantasy sequence in Chapter 494. He forms a friend group with classmates Chiarai Shigeo and Sonoda Taisei. The trio is prominently featured in Chapters 75 and 77, discussing which female classmates, including Najimi, would be ideal to date. Shinobino actively demonstrates ninja-like abilities, showcasing exceptional throwing accuracy – landing a compass precisely between Tadano’s thumb and index finger and hitting a target with a shuriken in front of Naruse. His athleticism allows for impressive high jumps, further emphasizing his persona. In Chapter 58, Shinobino proposes that Tadano form the "Komi Bodyguards," a group dedicated to protecting Komi Shouko, and later appears as a member alongside Kishi Himeko, Samurai Sam, and an unnamed maid girl. A notable interaction occurs during a king game in Chapter 98 when Tadano kisses Shinobino on the cheek. His name, Mono Shinobino, functions as a homonym for "shinobi no mono," a historical term for individuals trained in stealth for espionage or sabotage, aligning thematically with his character. His role remains consistently that of a background character across all seasons and manga chapters, with no significant development or expanded backstory provided in spin-offs or additional media.