Ninju (忍にん獣じゅうムキムキねずみ Ninjū Mukimuki Nezumi?) – also called Shino Buff Mice – are intelligent mice who work for Tengen Uzui . They made their first appearance during training.
The mice are specially trained to be assistants to Tengen and his acquaintances, as seen during the events of Yoshiwara, Tokyo. They are strong enough to carry one sword per mouse and are able to navigate small spaces that humans could not normally reach.