i am getting a full sleeve with a theme of evil. i am getting a hannya like this on the same spot

http://news.deviantart.com/article/43615/?offset=0#/d15amus
i am going to change it up a bit, but keep the general evil look to it.

i need more ideas for things on my sleeve to fill it out and i want it to flow well. not just random things put on my arm. The only other images i can think of which would match my theme are oni demons. Can any of you guys help me out with ideas please?