In a world where sinister Teropterids disguise themselves as humans to quench their thirst for human blood, hope shines through in the form of dedicated factions committed to eradicating them. Enter Saya, a enigmatic and skilled hunter renowned for her prowess in dispatching Teropterids. Tasked with a mission in 1960s Japan, she ventures to a U.S. military base suspected of harboring these malevolent creatures, poised to confront the lurking threat within its walls.