I got him down to purple. I've played Shinobi 3 and seems abit easier but I want to go through them in order.
Awesome boss music (Image removed from quote.)
IIRC, the trick is just to do the double-jump shuriken spray. I don't know if you set it to infinite shuriken or not, though. Also, don't forget to save your spell and use the electricity shield so you can take an extra three hits. If you can get to him with a POW on, that also makes a huge difference.
You will use up all yer darts really quick that way but it helps...
1st - lightining magic...
2nd - 2 to 3 jump shuriken spray's
3rd - move in and jump away when he swings, then run in duck and swing the sword/kick up close over and over but jump away before he swings
repeat last step till dead.
R o S is my fav Shinobi game. I finished it like 50 times on the Genesis and could complete the entire game on one life.