Kazuma Arashiba, bearing a surname meaning "storm brushwood," operates within the lawless Akatsuki Special Zone as a member of the organization Helios. He manages the book café "Titan" on behalf of his brother-in-law, Eiji Arashiba, and other associates. Kazuma harbors strong admiration for Eiji but frequently displays anger and emotional volatility, often appearing stressed. Despite this, he possesses a serious and gentle side, though he struggles to interact with children and rarely outwardly shows his caring nature.

In appearance, Kazuma has dark brown, nearly black hair reaching his neck and distinctive purple or pinkish eyes accentuated by long lashes. He typically wears a leather jacket and a studded belt, carries a katana with a red grip, and has a pale complexion.

Kazuma bears the divine tattoo "Cat Sith" (ケットシー, Kettoshī), inherited from Banri Mikado. This power allows him to inhibit and seal the abilities granted by other divine tattoos, making him crucial in confrontations involving other Scards.

Following Eiji's departure, Kazuma navigates his evolving role within Helios, forming a complex relationship with Yamato Kai, the new inheritor of Eiji's tattoo. Their dynamic shifts from initial tension to a layered rivalry and partnership, particularly during escalating conflicts with antagonistic groups like Dusk.