River Zastory

River Zastory is a sweeper interested in capturing Creed Diskenth and a former member of the Sweeper's Alliance.

In the manga, River is a a serious, noble man, willing to risk his life in order to save both friends and strangers. He is very competitive and views Train as a rival, but respects him regardless.

In the anime, River has more of a carefree attitude. However, should the occasion arise, he will complete the job given to him. He is also noble and kind-hearted, as shown when he tended to a lost child and tried to help her in anyway he can.