Funny how kappa have managed to become cuddly, huggable characters these days, considering their origins as monsters who ate victims' organs via their anuses... but even humans have become more civilized over the years, perhaps kappas have decided to do the same.
Japan has a whole ton of monsters, though - interesting "monster culture" considering that China has comparatively less (well, in modern times, few people know of any). One of my favorites is the "shirime," a critter that looks like a travelling monk - until he "moons" victims with his strange arse, which features a single large eyeball in the center, after which he (?) flees. We can even perhaps give it AD&D stats as follows:
Frequency: Rare; No. Appearing: 1; HD 1; THAC0 19; Damage per weapon (staff); SA: Stun victims 20' range for 1 round by showing strange arse (save vs. paralyzation at +3, +6 if not first time); SD: None.
Once DC is past 1.0 and creating other classes becomes possible at some point, it would be fun to have OA adventures for DC, too
(I can then use my few Asian-themed icons, i.e. the nupperibo, ogre mage, and ki-rin.)
Actually, one of my gripes with OA was that many monsters already represented in AD&D normal rules were re-added in OA with different names and stats - such as the oriental dragons (I was happy with the gold and mist dragons already), oni (the ogre mage was this already), and so on. It was also too Japan-centrified, perhaps because of the main author's (François Marcela-Froideval's) preferences.