Assassins Creed - Shinobi

My fifth work, stating to get the hang of this, this is my idea of what the Japanese branch of the Assassins might look like.
Sketched in pen and painted over on a multiply layer in PS, if you got suggestions on how i can improve be sure to tell me, thanx

Name: Taka Fujioka
Age: 21
Favorited weapon: Hidden blade ( of course)