Nazo no Murasamejō
謎の村雨城 - Japanese spelling
Nazo no Murasamejou is a fast-paced action game that has some similarities with The Legend of Zelda, although it is faster and has none of the RPG/Adventure elements. It is also much more linear: You fight through the castles one after the other, with each stage consisting of the path to the castle and the castle itself, where the boss is waiting.
Your have two weapons: (unlimited) shurikens for ranged attacks and a sword for melee combat. The sword is automatically used when you are close enough to an enemy, and it can also be used to deflect enemy shurikens. But since you are constantly under attack by ninjas from all directions and also have only a limited time to finish each stage, the game is still quite hard.