The reality is that bathrooms in Japan aren't as simple as they appear. There are lots of monsters, demons and ghosts in Japanese bathrooms. It's important to be prepared if you hope to escape. One monster (to prepare yourself for) is Aka Manto (Red Cape).
Aka Manto was a good looking man in life. He was constantly stalked by admirers. In death he wears a mask and red cape.
Aka Manto appears as a mysterious voice in the last stall of a bathroom. He asks "red vest or blue vest?".
If you answer red you will be sliced apart until your clothing runs red. If you answer blue you will be strangled until your face turns blue. If you try to trick Aka Manto by answering another color you will be dragged into the netherworld. The only answer that leaves you safe is "no vest".
VariationsAs with most urban legends, there are countless variations of Aka Manto. In one version he asks "red paper or blue paper?".