Odagiri Itaru, an elementary teacher, visited his student Aoyagi Rikuto's house to find out the reason behind Rikuto always sleeping in class. To his surprise, Rikuto was always helping his mangaka father, Aoyagi Kaiji, with his works. From then on, Odagiri always came over to their house to make sure that Rikuto slept on time. As time went by, Odagiri developed feelings for Kaiji. But will he be able to become that irreplaceable existence in Kaiji's heart?