The Ninja Chapter is pretty cool! It's ninja-ish like Ninja Scroll, involving bizarre ninjas with supernatural powers. Your job is to invade a fortress and battle against the hordes of ninjas. Actually, you don't have to battle them if you don't want you. Once you run from a battle, you need to run away because the enemy is still there and will chase after you. If you reach the top of the fortress without killing anyone, then you're awarded with a strong sword. But to be honest, it's not worth it. This chapter is much more entertaining to fight anyone you encounter so you can level up and learn nifty ninja techniques. This guy's special ability is to pull an invisible cloak over him to disappear (although you can't move around while doing so). You may want to skim through a walkthrough before playing this chapter. This fortress has tons of traps; when you fall victim to one, you die and have to start over.
Pro-Tip: The GenjiArmor allows you to gain HP when you get damaged by fire tiles. Your 3rd technique covers half of the battlefield with fire tiles, so use that in every battle to act as a Regen spell. As a bonus, the fire tiles will damage the enemy each time you Regen.

Note: The following screen shots are from an older version of Live-A-Live's English translation. The newer translation looks nicer!