Shinryu Sekijin commands the Shinryu household as its patriarch and protective older brother to Shinryu Shouken, driven by a relentless quest to avenge the Tanmoku family’s atrocities against his sibling. Their exploitation of Shouken as a disposable "blood bag" for Tanmoku Ki fuels Sekijin’s ruthless campaign to reclaim his brother’s remains and pursue shadowed rituals to resurrect him.

Though decades span their ages, Sekijin’s bond with Shouken intertwines stern authority with unyielding devotion, his every action propelled by an obsessive determination to undo the harm inflicted upon his kin. This compulsion initially drives him to broker Shouken’s fateful placement within the Tanmoku household—a decision that forges a pivotal link between the families before curdling into bitter strife. The revelation of Shouken’s torment transforms Sekijin’s calculated alliance into a catalyst for vengeance, cementing his role as both architect and avenger in the escalating feud between the Shinryu and Tanmoku lineages.