FoxSan's Manga

Mitsuru, who moved to Tokyo from Osaka and joined the sales department of a fairly large company, does his job perfectly. He has a knack for sales, and successfully acquires one large contract after another.
One day, he wins a contract with the industry's biggest company. Everyone celebrates his success at a company drinking party, after which Mitsuru decides to drink more at the apartment of junior employee Yuichiro.
Outside of work, Mitsuru is different around Yuichiro, who also happens to have been in the year below him at the high school in his hometown, and allows the younger man to dote on him, which he does to perfection.
A conversation leads to Mitsuru suddenly wondering if Yuichiro has a crush on someone. However, the other man refuses to give a clear answer...
Despite being together almost every day for the last ten years, Mitsuru realizes he knows little about Yuichiro.
Out of curiosity, he tails the other man, but cannot believe what he sees...!