Tadayoshi Tooyama, nicknamed "Soldier," earned his moniker through acts of violence that landed him in Shōnan Special Reformatory: assaulting his mother’s abusive boyfriend and committing false imprisonment. His imposing frame and initial hostility toward senior inmate Rokurouta Sakuragi sparked clashes, but these gave way to profound respect for Sakuragi’s leadership and philosophy of perseverance. Inspired by his mentor, Tooyama pursued rigorous physical training with fellow inmate Mansaku Matsuura ("Cabbage"), determined to enlist in the military.

Inside the reformatory, Tooyama consistently shielded peers from harm, intercepting violent disputes or enduring physical punishment to protect others. Upon release, he joined the Japan Self-Defense Forces, achieving his goal. His military career halted abruptly when he shouldered blame for crimes orchestrated by a foreign syndicate to protect ally Mario Minakami, leading to reimprisonment. After early release facilitated by Ryuuji Nomoto ("Scam")’s legal efforts, Tooyama returned to Shōnan as a guard. Rejecting punitive approaches, he prioritized empathetic rehabilitation, offering emotional support and advocating fiercely for inmates’ rights.

Later life included marrying Meg Yokosuka, sister of former cellmate Jou Yokosuka ("Joe"), and fathering twins, solidifying his shift toward familial stability. Tooyama’s trajectory—from combative delinquent to compassionate guardian—remained rooted in unyielding discipline, steadfast loyalty, and self-sacrifice, hallmarks that defined his transformation into a pillar of resilience and guidance.