When I first time saw this strange creature was probably in the advertisement for a sake company, Kizakura. There are men and women with a turtle shell on their back. In other word, they looked to me turtle men.
I learnt soon that they were Kappa (河童), a yokai (妖怪/ ghost). The ones in the ads didn´t look scary but then I got to know other images of this creature.
With these illustrations, you definitely feel some bad spirits from Kappa. Kappa is a yokai commonly known in the most parts of Japan and the features are ;
1. About the size of a child.
2. Skin colour is green or reddish. Some Kappa are quite hairy.
3. They have a plate-like thing on the top of the head and this has to be wet. They
loose power when the plate gets dry.
4. Kappa have a short beak.
5. Kappa have a turtle shell on their back.
6. Both arms are connected and when one stretches, the other shrinks.
7. Love cucumbers.
8. Drag children into the water and pull out their bum balls.
9. They love sumo and are mischievous.
10. Sometimes they give human secret medicine as a return.
What scared me the most was “Pulling out your bum ball”. Shiriko-dama, written as 尻子玉 or 尻小玉 is an imaginative organ inside the anus (excuse me if you are eating). A human who was taken this organ away would be paralysed and die.
They explained to me that sometimes Kappa would hide inside the toilet tank and take shiridama when the person crouch over the hole. It really freaked me out. Whenever we went to the countryside and I found that they still had this old toilet which was just a hole, I stared into the black hole and tried to finish as quickly as possible.
In the modern Japan, Kappa has become something more adorable rather than a yokai. Probably for younger generations, kappa only reminds them a maki-zushi. Kappa-maki is inspired by kappa who´s favourite food is cucumber. This is now much more popular and common Kappa in Japan besides the folklore. So for now, enjoy your sushi but don´t forget to protect your bum ball from Kappa when you ever swim in a river!
References :
Legend of kappa : http://nazo108.sblo.jp/archives/201208-1.html
Kusenbo story : http://www.snk.or.jp/cda/mame/3tanusimaru/2kusenbou.html
Kappa and I : http://morinokakera.jp/blog/?p=55670