Traveling in-between the world of the living and the twilight world of the dead, Akamushi, the shaman known as the Red Spider Exorcist, wields the powers of a giant spider to combat the demons of the netherworld. In a serendipitous moment, a young girl meets Akamushi, and falls in love with him at first sight. However, it turns out her grandfather and mother are haunted by a ‘Waraigao’ - a demon that attacks living human bodies from the inside, eroding and eventually deteriorating them.