The “burden” of the hunting guild, Jekyll, continues his work as a hunter to support his only family—his younger sister. Despite being looked down upon and ridiculed by those around him, Jekyll endured it all, desperately facing the challenges of monster hunting. However, one day, he is suddenly told about his limited “lifespan.” Standing on the brink of despair, Jekyll is approached by a demon who offers him a “deal.” What choice will Jekyll make to change his fate—!?