Rihaku del Mare, titled Rihaku of the Ocean, commands as the military strategist of the Nanto Goshasei, a guardian order sworn to shield the Last Nanto General, Yuria. He devises intricate defensive schemes and engineered traps to deter threats such as Raoh, though futile against the warlord’s unmatched power. A decisive clash with Raoh nearly claims his life until Kenshiro intervenes, revealing the Hokuto Shinken’s Musō Tensei—a turning point that etches Rihaku’s reliance on this transcendent technique into his strategic calculus.

Within the OVA timeline, Rihaku assumes guardianship of Yuria after her liberation from Southern Cross, following Shin’s surrender of her custody. He steers her ascension as the Last Nanto General, upholding the ancient decree of Nanto and Hokuto’s destined alliance amid chaos. His counsel spans tactical and political realms, including dissuading Yuria from disclosing Kenshiro’s identity to Rei—a caution overridden by her prophetic insight.

Rihaku’s past hints at a daughter, Tō, though their bond remains undefined. Post-Goshasei’s disbandment, he integrates into Lin and Bat’s Hokuto Army, evolving from a custodian of Nanto’s heritage to a linchpin in stabilizing the wasteland’s fractured hierarchies. His martial discipline, Gosha Hasui Ken, surfaces briefly in clashes against Raoh, underscoring resolve despite its tactical limitations.

Pivotal junctures mark his journey: he stands witness as Yuria confronts Tobi’s symbolic mantle as the "Dog of Destiny," silently affirming the creature’s role amid the moment’s dissonant gravity. Later, he aids Kenshiro’s recuperation post-battles against Souther and Raoh, cementing his function as a conduit between Nanto’s legacy and the Hokuto-driven upheavals reshaping the world.

Through all iterations, Rihaku endures—a tactical realist anchored by unyielding loyalty to Nanto’s ethos. As the sole surviving Goshasei, he observes the metamorphosis of power and hope within the saga’s unfolding lore.