Berserker's identity is Tamamo Cat (タマモキャット?), one of the Tamamo Nine. She is the crystallization of Tamamo's more pure and sincere aspects.
A member of the Tamamo Nine. After Tamamo-no-Mae underwent a millenium of training and attained divinity, she cuts off her other 8 tails when she returns to her one-tailed form. Each of her tails is left a portion of her divinity and becomes a heroic spirit.
Something like a wild cat that one cannot tell what it wants to do, nor what sort of mess it will make.
As it is a Berserker, it is basically difficult to come to a mutual understanding.
Show no interest anything but tasty things, fun things, everyday fully enjoying a hunting lifestyle according to her whims.
As a dignity of a wild beast, once someone is served as a "lord", she devotes her allegiance until the end.
After forming a contract, Tamamo-Cat will turn into a guardian beast that wants nothing but to be helpful to her master.
Once things become like this, protecting the Master, the happiness of the Master becomes foremost and Cat stops thinking about her own joy.