Seiichi Kuze, reigning as the most decorated Japanese sumo wrestler in history under his ring name Yamatokuni, claimed 31 championship titles as a yokozuna. His signature sumo style blended a low center of gravity with tactical precision, notably utilizing the Left Arm Clamp to position opponents for throws while consciously moderating his strength to prevent injury. This disciplined approach clashed with his son Sosuke Kuze’s early recklessness, prompting Yamatokuni to bar Sosuke from competition until he proved restraint during a pivotal Inter-High Tournament bout against Shidō.

Yamatokuni’s storied career concluded abruptly following a decisive defeat by Mongolian yokozuna Jino, after which he retired and shifted to coaching. He mentored Hinomaru Ushio in middle school, emphasizing technical fundamentals and mental resilience—key elements that shaped Hinomaru’s ability to compensate for physical disadvantages through adaptable tactics.

Initially wary of Sosuke’s sumo ambitions due to concerns over impulsiveness, Yamatokuni reevaluated their relationship after witnessing Sosuke’s measured performance against Shidō, transitioning from overprotective guardian to supportive father. This shift mirrored his broader legacy: a retired icon navigating his past achievements while cultivating future talent.

His enduring influence permeated the sumo world beyond direct mentorship. Figures such as Tsukasa Yamatogo, part of the Yamatokuni Stable’s "Three Great Spears," exemplified his lasting imprint on the sport’s competitive hierarchy.