The Kaibutsu are white-haired and pale-skinned (bearing much likeness to Sabitsuki) that wear the uniforms of schoolchildren. Their appearances vary from regular humans with bloody faces (interacting with them does not trap you in enclosed areas), to demon-like malevolent pursuers with bloody faces that appear to be smashed in (due to their transformation of their 'calm' state to 'crazy' only occurring when the iron pipe effect is used on them). Kaibutsu only chase after Sabitsuki when in 'crazy' form.
- Kaibutsu translates literally into 'monster'.
- Initially .flow's answer to Yume Nikki's Toriningen, the Kaibutsu have become far more than standard enemies over the course of the game's development.
- The Kaibutsu found in the Bone Maze after the Hospital will become extremely fast when angered. Because its behavior is similar to the Toriningen found in the Candle World in Yume Nikki, this one is sometimes nicknamed the 'Candle World Kaibutsu'.