Yes, Japan's bathrooms are haunted by an eclectic mix of spirits, ghouls and monsters. Some are shy, some are violent, and at least one wants to lick up your tub grime. So, ranging from least to most dangerous, here are six of them that you may just end up meeting the next time nature calls.
6) Toilet Hanako
Hanako is a popular subject for Japanese pop culture. There is a series of horror movies based on a more sinister version of the legend, and she also pops up in several anime and manga. In the anime Haunted Junction, Hanako is portrayed as a sultry and busty teenager in a too small (and too tight) school uniform. The little toilet ghost fares a bit better as one of the stars in the manga Hanako and the Terror of Allegory; she's still a young girl, but she is given incredible supernatural hacking powers and the power to teleport between any two toilets in the world.
The Japanese are able to turn anything cute, even a monster like this. In the manga Neko Musume Michikusa Nikki (Cat Girl Michikusa Nikki), Akaname is cast as a cute little tan boy with blond bristle hair and a huge tongue that likes to lick filth off everything (including cat girls). Also strangely enough, Akaname takes the title role in a British-based children's book called The Filth Licker by Cristy Burne.
The trickster tanuki in Studio Ghibli's Pon Poko movie use the image of noppera-bos to try to scare away some construction workers threatening their home. Faceless aliens in one of the Hetalia movies are called "nopperas." The image of a face with only a mouth also shows up in a lot of shows, a well-known example being that of the Gate (or Truth) character in Fullmetal Alchemist.
In the anime Haunted Junction the character Red Mantle is based on Aka-manto, and (much like Toilet Hanako) is given a sexy makeover that inspires lust in every girl in the series save the female lead. Aka-manto also appears as a demon character in the Shin Megami Tensei videogame series.
Since they are so similar, elements of Akai-kami-Aoi-kami's story is often mixed in with Aka-Manto, but the monster does make a rare solo appearance in an episode of the Ghost Stories anime. Basically, if anyone (or anything) asks you a question in a Japanese restroom, run like hell.
1) Reiko Kashima
Be warned: Much like Sadako from The Ring, this next monster is said to come after anyone who hears about her. Reiko Kashima is a legless ghost, and much like others on this list, asks anyone encountering her a series of questions. Answer wrong and she twists off your legs. She is said to have once been a normal woman who was beaten and/or raped by a large group of men and left for dead. She crawled away, only to collapse on some railroad tracks, where a train came and cut off her legs. Now she wanders the bathrooms of the world, searching for her missing legs.
Since she is still rather new, Reiko hasn't built up quite the resume the others on this list have. Still Reiko is mentioned in the Persona videogame series and is a character in its sister series, Shin Megami Tensei. There is a Japanese horror film series called Teke Teke that mixes up elements of a similar legless monster (the Teketeke, naturally) and the Reiko Kashima legend.