All you have to do is, go behind a a red piller then wait for the boss to strike the red piller. His sword is going to get stuck on the piller and he is trying to pull it out, while he is trying to pull it out. Your going to walk on his sword intill you see a mouse icon thing come out on your side of your screen saying right click. When you right click its going to tell you to keep tapping the space button, when you do that the ninja is going to run up his arm and behind him and you press the left mouse button, your going to hit him in the face. After that I think your going to fall down and you have to hit him on the butt, when you get to that part it tells you what buttons to press. You do that process 3 times then your done with the boss. Sorry if its bit messy But, I hope it helped out.