A crashed alien ship buried beneath feudal Japan turns ninja into something stranger than myth. Psychic assassins fighting extraterrestrial invaders in underground tunnels is the kind of premise that only works if you commit completely to it, and this OVA does. The show treats ancient bloodlines and alien warfare as the same historical fact, refuses to explain the contradiction, and moves on. You're either in on the conspiracy or you're not watching. Real 80s sci-fi energy that doesn't bother justifying why ninjas and aliens share the same underground empire for thousands of years.
Beneath Japan's surface, an underground civilization thrives in secret. For centuries, ninja clans have guarded their hidden world, their true purpose shrouded in shadow. When a massive alien vessel crashes into their territory, dormant for millennia, everything changes. The extraterrestrial occupants awaken, and suddenly the assassins must weaponize their psychic abilities and combat training against a threat unlike anything their ancestors faced. Miroku follows elite ninja warriors as they navigate both their internal clan politics and an unprecedented war against hostile alien forces. Ancient ninja traditions collide with advanced alien technology in brutal, visceral combat sequences. The psychic elements give fights an eerie, otherworldly dimension, where mental warfare proves as deadly as steel. This is ninja fiction reimagined through a science fiction lens, blending feudal mysticism with cosmic horror. The tone shifts between tactical intrigue and explosive action, grounded by a cast operating under constant existential pressure. It's for viewers drawn to unconventional premises where historical fantasy meets alien invasion, told with the raw energy and ambition of late-80s anime production.