Warechu is a small gray mouse with big red eyes and two white whiskers on each cheek. His chest is a red and yellow broken heart marking and he wears red boots. While he has black coloring on his arms, legs, and inside of his ears. He has two small reddish purple demon wings and a rat-like tail with a big black heart on the end and a zig-zag split in the center.
Warashu is a confident mouse and he is loyal to Arfoire, but is quick to retreat should he lose a battle.
He has a crush on Compa, believing her to be an angel after she offered to heal his wounds and holds her in high esteem, even when she views him as an enemy.
- His apprearance may be a reference to Pikachu from Pokémon and Mickey Mouse of Disney fame.