Shirime is a ghost with no face and an eye on its bottom. The name "Shirime" is made with two kanji characters, 尻目. When translated, it literally means "Butt Eye".
The story goes that, many years ago, a brave samurai was walking to Kyoto alone late at night. Suddenly, a strange man stepped onto the samurai's path from the shadows.
"Who goes there?" demanded the warrior, hand on his sword.
"Excuse me. Can I have a moment of your time?" said the stranger.
Before the samurai could answer, the man began striping and bent over, effectively mooning the dumbfounded warrior. Peering at the samurai was a huge, glowing eyeball. The man had no face. Seeing this, the samurai ran away as fast as he could, screaming.
This ghost is famous because, unlike most ghosts in Japan, it doesn't kill its victims. It just scares them.