Taking place after the events of the fourth film, the series centers on 11 yr old Keisuke Amano, Natsume's younger brother (both of whom are the children of Keita Amano and Fumika Kodama of the original Youkai Watch anime) who doesn't believe in any supernatural phenomenon around him. But as he notices his sister is frequently comes back home late, he decided to stalk her, only to find out she is doing her duties exo...