Himari Noihara has a demon like cat beast within her. When she is in rage, it increases every physical aspect of her body.
When Himari loses her sanity during a battle, she turns into a berserker cat with an uncontrollable bloodlust, which Shizuku states it is her true nature, a demon who gains pleasure from hunting and losing herself in bloodshed and that the more she fights, the more she reverts to her kind's killer instincts to the point that she loses herself completely. She is depicted with a dark aura surrounding her body in addition to her having red eyes when she reaches this state. Himari has half control over her body, but can return to normal.
At the most of the time, Himari demonstrated the ability to manifest cat ears and tail without losing control. The ears and tail are also visible when she is wearing her Strikers.
During one of her battles against two members of the Akatsuki, she changed to a demonic form known as "Demon Himari". Demon Himari is Himari's true demon form, which consists of her having white hair, a paler skin complexion, red claws, black tribal markings on her skin, and a bushier tail. In this state, her demon powers are pushed to their absolute limits and she can perform powerful claw swipes from a distance. However, due to her losing control of herself after losing her sanity, she will attack anyone she sees regardless if they are friend or foe and she is extremely dangerous because of this.