Mizunoguchi is sadistic dentist and Euphoric user who has been given extra spider-like limbs with dental devices on them and can even turn other part of his body into drills (such as his tongue). He tortures patients by inserting all of his limbs into their mouths and polishing their teeth slowly. Apparently he removed Kagura's lower molars three years ago, but did it as slow as he could so he could see Kagura writhing in pain. He kept one of them as a crown jewel of sorts and carves it obsessively.

(Source: Wikipedia)