The Ninja Gaiden NES synopsis centers on ninja Ryu Hayabusa seeking vengeance for his father, who has been killed by the evil cult leader Jaquio. After traveling to America, Ryu learns that his father and an archaeologist, Dr. Smith, hid two statues that, when combined by Jaquio, can summon an ancient demon. Ryu must battle through 20 levels using his Dragon Sword and ninja magic to stop Jaquio and the demon from destroying the world.