Kappa are aquatic monster girls from the marshes and rivers of Zipangu. They are specifically cited in the Early settings info as typifying the "neighbourly" monsters who freely intermingle with humans in that eastern land. Like the yuki onna, it's particularly their young who enjoy intermingling with human children. It's not quite right to say that kappa are non-violent, because a young kappa's preferred form of interaction is to play sumo with boys, practicing the skills that will one day see her come back and really push down her favourite opponent.
Like the wererabbit, kappas have a natural fondness for phallic-shaped vegetables, in their case cucumbers.
An aquatic type monster that inhabits watery areas like marshes and rivers throughout the land of Zipangu. Its form is close to human, but it has green skin and carries a round, dish-like object on top of their head. They also have a shell, and webbed feet allowing it to swim effortlessly.
Most of them are mischievous and have a strong willed personality, but they aren't very violent. Kappa children often intermingle and play with human children. They especially like playing a game popular in Zipangu called "sumo" which involves pushing one's opponent out of a ring, or pushing one's opponent down. Compared to human girls their bodies are far more robust, and with their mighty strength they can even pin boys down.
But don’t let yourself be fooled, they are monsters and as far as they are concerned, the children they meet are just future marks. Through their socialization with human children, they unconsciously decide who they will have as their husband.
Even when they push boys down and pin them down during sumo, they experience a powerful arousal that they can't quite understand themselves. Their devilish nature is unconsciously awaiting the future when they will pin down a man in the same way and have sex with him. Once they have grown a certain amount, their lust suddenly swells greatly. They will go into heat and assault the man they targeted during childhood in an attempt to force intercourse.
Additionally, while their body is wet, their physical abilities increase, and when their scales that appear like clothing get wet, they squeeze their body, producing arousal and increasing lust; so they are extremely dangerous when near the water. If they sight their mark approaching the water’s edge, they will drag him in immediately and try to initiate sexual intercourse. One must be very cautious.
The dishes they carry on their heads are always wet with water. The dish is their weak point. If it dries up, not only will they lose strength, but she’ll also become extremely sensitive to stimulation. Touch the area, and she’ll no longer be able to move.
The kappa strongly prefer the vegetable known as the cucumber. Especially when they're very little they're often seen with a cucumber in their mouth. According to one explanation, it may be that rather than the taste it has more to do with the shape of the cucumber; which they are instinctively drawn to due to their devilish nature. It is also said that kappa during childhood may especially prefer cucumbers because its something they can practice with for when they have sex with a man in the future.
- This monster girl is based on a yōkai in Japanese folklore.