Ninja Kaijin looks like one of the Minions of Maoh, except his skin is white and he wears ninja outerwear such as a gappa and zukin.
Ninja Kaijin was the forty-ninth monster to battle Greenman. He was created by Tonchiki and sent to retrieve the blood of children for Maoh. The Ninja Kaijin and its creator began to terrorize the kids before two of them used their Green Calls and summoned Greenman to protect them. Eventually the hero came out victorious.
- Ninja Kaijin is the second of a set of five 'unique' Minions of Maoh to battle Greenman. He is preceded by the Cross-Dressing Kaijin, and followed by the Magic Kaijin, Pattern Kaijin and Alter Ego Maoh.