Rainenmaru

Rainenmaru was one of Suien's summons who appeared in Naruto: Mission: Protect The Waterfall Village! (novel).

Personality
Rainenmaru was very loyal to Suien. He was also violent against his opponents, as seen when he attacked Naruto Uzumaki and Sasuke Uchiha with his whiskers while they were riding on Ryūrimaru.

Appearance
Rainenmaru was giant black koi.

Abilities
Rainenmaru had incredible speed, able to take down Ryūrimaru and Naruto with one blow.