Doruku stands as a primary antagonist in Super Mashin Hero Wataru. He is the middle son of the Donarukami Family, the group commanding Soukaizan. His face remains concealed behind a dark purple mask and light purple cap-like helmet, beneath which flows long, wavy blonde hair. He wears a green robe over purple and orange shorts and a T-shirt, secured by an orange belt worn over the robe that sheathes his sword.

Notably quiet and reserved, Doruku distances himself from others, contrasting his brothers' more argumentative natures. His singular focus rests on defeating protagonist Wataru, treating this as his paramount duty. A dedicated and honor-bound swordsman, he approaches combat with intense seriousness. He harbors a strong aversion to pity from opponents, preferring death to perceived condescension, and actively rejects offers of kindness or friendship.

Within his family, Doruku displays indifference toward his brothers Dohdo and Doran, showing little interest in their disputes and generally avoiding interaction. He holds particular disdain for elder brother Doran due to Doran's condescending attitude and a past attempt on Doruku's life. Despite this initial hostility and detachment, the brothers ultimately resolve their conflicts, establishing peaceful coexistence.

Doruku's journey transitions him from an isolated, duty-bound antagonist solely focused on eliminating Wataru and upholding the Donarukami rule to navigating fraught fraternal relationships. The resolution of these conflicts marks a shift toward mutual understanding and coexistence among the brothers.