Kenichi Shirahama starts as a timid, bullied teenager who avoids confrontation, finding solace in self-help books and tending plants. His path alters when Miu Fūrinji, a martial arts prodigy, draws him into Ryōzanpaku—a dojo sheltering masters of varied combat traditions. Though intimidated by the dojo’s brutal regimen and unconventional teachers, he gradually adopts martial arts to shield others, guided by an unyielding ethic: never strike girls or bespectacled foes, a creed that sometimes hinders his fights. A fractured childhood bond with Ryūto Asamiya and a fateful exchange with Miu—trading a cat badge for her yin-yang pendant—subtly prefigure his future. The badge anchors his determination, its full meaning dawning only years later. Under six Ryōzanpaku masters specializing in karate, jujutsu, Muay Thai, Chinese kenpō, weaponry, and combat philosophy, Kenichi forges a hybrid style—the *Saikyō Combo*. Devoid of natural aptitude, his tenacity and ingenuity let him outfight seasoned adversaries. Relentless conditioning builds inhuman endurance, letting him absorb brutal blows while outlasting opponents. His evolution from fragility to fortitude unfolds through clashes with bullies and the Ragnarok gang, victories marred by lingering insecurity. Uncompromising mercy toward enemies—even former aggressors like Takeda and Ukita—turns rivals into allies. This empathy extends to YOMI, disciples of the shadowy Yami group, as his compassion disarms hostility. Complex bonds emerge: mutual affection with Miu deepens amid shared peril, while Renka Ma and Yūka Izumi harbor unspoken feelings he scarcely notices. Years later, he weds Miu after besting her grandfather in combat, fulfilling the elder’s stipulation for her hand. Global confrontations with Yami’s schemes culminate in the disbanding of both Yami and Ryōzanpaku. Post-war, Kenichi trains while penning novels, his legacy defined by *katsujin-ken*—the principle of using martial arts to protect, not dominate. Physically, he transforms from frail to leanly muscular, his wardrobe blending elements from each mentor’s art—a tapestry of his eclectic training. A perpetual bandage beneath his left eye and Miu’s gifted wrist wraps silently attest to his struggles. Vulnerable to self-doubt and impulsive risks, he balances these flaws with mentors’ wisdom. Even after mastering techniques like the *Ryūsui Seikūken*, he credits perseverance over talent, humbly rising to surpass Hayato Fūrinji and cement his mastery without forsaking integrity.