Setsuna Kai has to move to a new city and live independently in an apartment due to family circumstances. However, upon his arrival, he experiences an unusual incident where rocks aggressively come down, and he barely escapes a boulder from crushing him. Unfortunately, his new abode did not survive this bizarre rain. Setsuna is lost and confused, until he meets a scientist, Dr. Hiromi Kaname. Dr. Kaname's technology detects Setsuna's "Devil Child" abilities, leading to his decision to take Setsuna to his laboratory.