Meisuke 'Nube' Nueno, a teacher at Doumori Elementary School and expert in the occult, finds it increasingly difficult to protect his students against dark forces. After one of his students is sent to a parallel world, Nube encounters an unusual spirit that sends him back in time to change one regretful event.Although Nube manages to fix the situation, this succession of unlikely events suggests that a more serious menace may be threatening the peace of Doumori. To protect everyone he holds dear, Nube will have to overcome the demons of his past and uncover the nature of the looming supernatural danger.