Dame na Kurai ga Choudoii

Odagiri Itaru, an elementary sensei, went to his student, Aoyagi Rikuto’s house for a house visit to find out the reason that Rikuto was always sleeping in class. To his surprise, Rikuto was always helping his mangaka father, Aoyagi Kaiji, on his works. Odagiri always came over to their house to make sure that Rikuto slept on time. As time went by, Odagiri started to have feelings for Kaiji. But would he be able to become that irreplaceable existence in Kaiji’s heart?
(from Attractive Fascinante)