Appearing in Episode 23, Setsura hails from the otherworldly civilization of Teoti and stands as its only named citizen within the narrative. His name forms an anagram of "Rasetsu," the Japanese term for the Hindu demigod Rakshasa.

Initially serving Teoti leadership, Setsura becomes embroiled in their conflict against humanity. During a pivotal confrontation in Episode 29, antagonist Valtom captures him. Valtom seeks to execute Setsura by binding him to a stone and unleashing giant centipedes. This act triggers a shift in allegiance; fellow Teoti member Sougyoku defies orders to secretly rescue Setsura and spirit him away.

Setsura's perceived death during this ordeal deeply affects human ally Abuto Usui. Consumed by rage over Setsura's supposed demise, Abuto pilots the corrupting Dark Shinkalion mecha. This machine intensifies his fury, driving him to confront his former allies. Setsura's survival and his subsequent role in the broader conflict remain unexplored in the provided materials.