Yuta used to be very shy and reserved when he was younger. He grew up this way after the death of his best friend Rika Orimoto, still in childhood. After a fatal accident, Rika's spirit remained on the mortal plane, permanently linked to Yuta. This turned her into a Special Grade Curse, showing herself as a powerful vengeful spirit, dedicated to defending Yuta from all evil. However, Yuta began to have difficulty interacting with other people, and grew up isolated.