Can a sweet and lovely girl actually be a cold-blooded killing machine? In this technologically advanced age, humans begin to study mutants, and the heroine is one of the less successful experiments. The heroine loses her memory and meets the hero by chance. He doesn't dislike Seraphina "Sera" Bellweather's innocence, but carefully teaches her and puts her on the right path, awakens the humanity deep in Seraphina "Sera" Bellweather's heart, joins forces to save more "Subjects", and successfully destroys the secret research institute.