Sehnsucht nach ihm

Salaryman Hoshina has been sharing an apartment and a bed with model Atsushi. Atsushi cooks, cleans, and remembers every anniversary, but Hoshina can't figure out why they are in this "type" of relationship. When Hoshina's younger brother moves in for a while, and the boys must endure until he's gone, will Hoshina even care? Will this time of separation be the turning point in their relationship? And which will boi will be the one screaming, "Once is not enough"?