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 and Sasuke with his whiskers while they were riding on Ryurimaru.

Appearance
Rainenmaru was giant black koi with black skin.

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