Sanbonmatsu Bantaro, a classmate of Jiyu Nanohana, positions himself as the spirited leader of a ragtag group featuring Kozaru, Oozaru, and eventually Shirou Ryujoji. Upon meeting Jiyu, he becomes instantly smitten, launching relentless—and perpetually thwarted—attempts to declare his affections, each derailed by absurdly timed mishaps. Undeterred by rejection, he shadows Jiyu with unwavering devotion, inserting himself into her endeavors at every turn.

When Bantaro’s group uncovers Jiyu’s secret legacy as the heir to Yagyu Jubei, he vows to aid her against relentless foes despite the peril, though his impulsive decisions and intellectual shortcomings render his assistance more symbolic than effective. This haplessness clashes with his inevitable future: inheriting his family’s centuries-old sake brewery, a responsibility awaiting him post-graduation.

His most striking feature is the animated kanji emblazoned across his shirt, which shift dynamically to mirror his emotions, circumstances, or dialogue. Interactions with Jiyu and his comrades frequently spiral into farce, highlighting his over-the-top loyalty and earnest yet inept efforts to contribute during clashes, often leaving chaos in his wake.