Yakusai ga Ore wo Aishiteru

A girl makes a desperate deal with a demon to save the boy she loves, giving him everything she possesses. The demon, seeking to understand human love, inhabits her body and attempts to build a genuine relationship with the boy. The boy, unaware at first of her absence, begins searching for a way to reclaim her from the demon. The two confront each other as the demon pursues its goal through her borrowed form.