Curiously, each Mouth Monster is found wandering around near a blood splatter, one for each individual. What this represents, as with everything else in the game, is a mystery. No Mouth Monsters are ever seen where there are other types of NPCs in the vicinity. The implication may be that they have eaten another creature and wear their hair as a trophy, which perhaps explains why Madotsuki can take it off them.
The Poop Hair Mouth Monster is a little different from the others. Not only is it found in a separate location than the other two, but its behaviour is slightly different, too - it will always move towards Madotsuki, whereas the others move randomly. Additionally, the Poop Hair effect has a different (1) Action to the other hair effects.
All three give effects that change Madotsuki's hairstyle when interacted with:
- The one with brown hair gives the Long Hair effect.
- The one with blonde hair gives the Blonde Hair effect.
- The one with the hairstyle that looks like a fake dog poop gives Madotsuki the Poop Hair effect.
- It is possible that the Mouth Monsters are based on a youkai called a Futakuchi-onna, which is a woman with a large mouth located in the hair at the back of her head.