Namahage
1968 anime:
Daisuke Azuma was a sharp kid, but not particularly well-mannered. One day he put on a Namahage mask he found at a shrine and started using it to mess with people. Things went too far when he accidentally scared an old man named Roppei so badly the guy seemed to drop dead. Panicked, Daisuke ripped off the mask—only to discover his own face had transformed into an actual Namahage's. Plot twist: Roppei wasn't dead at all. Turns out the old man was a real Namahage himself.
2007 anime:
He's one of the 13th-ranked Youkai Warriors chosen to represent the 47 regions of Japan, serving as Akita's representative.
Content compiled by AnimeList.moe from publicly available sources.