Read Kono Kaisha ni Suki na Hito ga Imasu Manga:
"Why don't the two of us date?......In secret"Tateishi, who works in accounting at a snack making company, has a secret. That secret is the existence of his cute lover that he's had since yesterday. Why keep it a secret, you ask? Because his lover is his unyielding colleague from the planning department of the same company: Mitsuya!A pure office romance story about a couple who started their more.. relationship in secret, and want to keep it that way!