Kowaru the Jiaaku stands among the primary antagonists in the series, the son of Guwaru the Ziarc and cousin of Hoto-ken. His kitsune-like demonic appearance reflects his nature. Kowaru exhibits consistently bratty and selfish traits, coupled with a notable degree of cunning inherited from his father.

He collaborates closely with his father and their servant Dogu, plotting schemes to steal the magical turban worn by the protagonist, Hat. Successfully obtaining the turban would enable his family's conquest goals, driving him to harass Hat and his companions at every opportunity.

Specific behavioral patterns include harboring a romantic fixation on Spin, another member of Hat's group, which Spin strategically exploits during their encounters. Kowaru also displays a strong aversion to vegetables, particularly green peppers, serving as a recurring detail.

His relationship with his father, Guwaru, extends to assisting in the banishment of King Aleph during an Underworld power struggle. This action directly triggers the fragmentation of Usontō into seven islands, igniting the core conflict driving the series' plot.