If you are at a loss, I can suggest some interesting Japanese demons, or you could look at this snazzy wiki about them:
(wiki is here)- Kuuketsuki (Japanese vampire)
- Ryuu (Japanese dragon)
- Mizuchi (dangerous water-dragon)
- Okami (wolf demon)
- Doji - (a spirit with white wings, accounted in European mythology as being like an angel)
- Kappa (a famous water monster with a water-filled head and a love of cucumbers)
- Bakeneko (shape shifting cat)
- Ningyo (a fish person or "mermaid")
- Tanuki (shape shifting raccoon dog)
Of course any Japanese animal can really be a demon with "youkai" thrown in at the end, like:
- Inu Youkai (dog demon)
- Tora Youkai (tiger demon)
- Kuma Youkai (bear demon)
- Saru Youkai (monkey demon)
- Hebi Youkai (snake demon)
Most of the ones I mentioned in the first section, there is more info on them in the above link.