Waiu is a humanoid ninja. He wears purple ninja garb, yellow shoes, and has yellow hands. His eyes are also yellow.
Waiu can throw cutter-esque crescents at Kirby, which can stick into the wall or fall to the ground; these can be inhaled and used as projectiles against him. He can throw one while standing or jump into the air and throw two. Another midair move Waiu possesses is similar to Fighter Kirby's Moon Somersault Kick attack; Waiu jumps into the air and flips around, performing a kick in the air. He can do this move once, twice in a row, or use the attack immediately after running up a wall.
Waiu can vanish, then rapidly flash overhead at different points on the screen, finally choosing a spot to appear in an attempt to land on Kirby. When he lands, a tiny star leading a trail of flame will bounce twice along the ground, then launch vertically into the air up to the top of the screen. This star cannot be inhaled. The ninja can also flip around and strike the ground, launching the same flaming star without him having to move much.