Katsutoshi Imai leads Benibane High School as its banchō. The eldest of four brothers, he towers at 189-192 cm with a physically imposing presence. He possesses immense strength but minimal intellect, which often triggers comedic or unfortunate outcomes. Despite initially handsome features, he consistently fails in romance due to frequent mishaps and poor judgment during social interactions, especially with women. He considers Takashi Mitsuhashi his sworn rival because Mitsuhashi mocks him and exploits his naivety for amusement. Their encounters usually leave Imai suffering misfortunes, leading him to actively avoid Mitsuhashi over time. In fights, he relies on raw power and endurance—hurling opponents or enduring heavy blows—yet seldom defeats major adversaries. Honesty, simplicity, and unwavering integrity define his personality. He tackles challenges with earnest effort and a straightforward mindset, free of deceit. This genuineness and perseverance gradually win him respect from peers and rivals. His loyal followers include Yasuo Tanigawa, who respects him wholeheartedly and pledges lifelong allegiance, and Taro Koyama, a formidable fighter who joins after Imai defeats him. Throughout the narrative, Imai undergoes significant development, evolving from a comedic figure into a respected individual. His journey involves navigating conflicts, enduring repeated humiliations, and upholding his moral principles despite provocations. This growth showcases his resilience and cements his role as one of the story’s most dynamically developed characters.