Don't Let Enemies see you as you make your way to the Exit door, be as stealthy as possible! well, you are a ninja, that shouldn't be hard :) . pick up Shurikens and use to your advantage, Enemies can't survive your deadly Shurikens, be sure to hit the right Enemy though, you can also pick up stones and use to Distract enemies, Enemies are drawn to stones, they'll go to inspect, use it to your advantage!