Every land has its Urban Legends and Japan is no exception. Oddly enough though, some of them center around the loo.
First up, there's 赤マント(Aka Manto or Red Cloak.) He appears, wearing a red cloak and a white mask and is said to be so charming that girls are unable to resist him. Red Cloak hides in the last stall of the girls’ toilet and when you enter, he steps out and asks “Which do you prefer, Red Cloak or Blue Cloak?”
If you say Red, he slits your throat or chops off your head and the blood flows down your back, making it look like you’re wearing a red cloak. If you say Blue, he grabs you by the neck and chokes you until your face turns blue and you die of suffocation.
Don’t even think about asking for a third color. If you do, the floor will open up beneath you and pale white hands will reach up and drag you down to hell.
In yet another version of the legend, he is called 赤紙青紙 (Akai Kami, Aoi kami or Red Paper, Blue Paper). Girls who go into the bathroom, hear a voice coming from the last stall. It asks “Do you want red paper or blue paper?” To answer red means a bloody death by being skinned alive. To answer blue means to have all the blood drained out of the body.
Next up is 仮死魔靈子 (Kashima Reiko), the ghost of a woman with no legs who haunts school bathrooms. Warning: They say that after you hear the story of Kashima Reiko, she will appear to you within a month. If you don’t want to see her, don’t read this.
Kashima Reiko is the ghost of a woman who lived in the city of Hokkaido, in Japan. One night, she was attacked by a group of men. The beat her badly, abused her horribly and then left her for dead.
She tried to call for help but nobody heard her. She tried to find someone to help her, but she crawled onto a railway track and collapsed, unconcious. The train came along and ran her over, killing her and cutting her in two. Her body was severed at the waist.
Ever since then, Kashima Reiko’s vengeful ghost has wandered the world, searching for her missing legs. She is mainly encountered in school bathrooms, but also may appear in your bathroom at home in the middle of the night.
When you enter the bathroom, she will ask you questions. If you cannot answer her questions correctly, she will tear off your legs.
To discover the questions & answers, head over to Scary for Kids
Another popular tale is トイレの花子さん (toire no Hanako-san)
A young girl raises her hand in class. She has to use the facilities.
As she walks down the hallway and enters the bathroom, she becomes uncomfortably aware that she is completely alone.
But an eerie feeling steals over her as she walks by the empty stalls -- one, two, three. As she walks, she gets the feeling that she is no longer alone, and there is a presence with her in the bathroom.
As she passes the fourth stall, she sees a gleaming pair of eyes staring back at her.
This is Hanako-san. (Lots of detail at that link.)
Found in every elementary school in Japan, Hanako-san, or more formally, トイレの花子さん (Toire no Hanako-san,) inhabits the fourth stall of the girl's bathroom.
The ubiquitous ghost is sometimes rumored to be the spirit of a suicide prompted by "ijime," or bullying.
You can watch one of the several movies made about her, starting here: (Keep an eye out for Chiaki Kuriyama as a little kid.)
Inevitably there was a sequel, Shinsei Toire no Hanako-san.
So next time you have to head to the Powder Room, beware of who might be waiting in the next stall!