Raijin Stable Master leads the Raijin sumo stable, bearing the imposing physique typical of former wrestlers elevated to this position.

His stern, disciplined nature reflects a profound dedication to sumo wrestling's traditions and demands. He initially presents as a strict, no-nonsense authority, frequently exasperated by Matsutaro Sakaguchi's wild conduct and initial disrespect for sumo customs.

Despite persistent frustration, he acknowledges Matsutaro's extraordinary raw power and potential. This insight motivates him to recruit Matsutaro into his stable, looking beyond the unruly exterior to glimpse a future champion.

He acts as a demanding mentor and trainer. He imposes rigorous training routines and enforces sumo etiquette rigorously, driving Matsutaro and his other wrestlers to their limits. His tough-love approach stems from a conviction that hardship and discipline forge true sumo wrestlers.

As Matsutaro matures and learns to focus his strength within the ring, the Stable Master's demeanor evolves subtly. While upholding strict standards, he develops a measure of gruff respect and paternal concern for Matsutaro's progress and welfare.

His mentorship extends beyond physical conditioning to include the strategic and spiritual dimensions of sumo. He guides Matsutaro through the ranks, manages his matches, and delivers crucial, often severe, feedback. He serves as a stabilizing influence, striving to counter Matsutaro's impulsiveness with wisdom drawn from his own deep sumo experience.

His background as a former wrestler shapes his methods, though specifics of his competitive past remain unelaborated. His sole focus is the development and triumph of his stable's wrestlers, particularly Matsutaro. He shepherds Matsutaro's transformation from a delinquent into a dedicated rikishi with unwavering, albeit tough, commitment.