Dou Shiyou mo Nai Keredo(2005)

Hardworking, good-looking, and heir to daddy's company, Shimano thinks his life's just about perfect. Except that he's working from the bottom up in the company, and he can't seem to get along with Kurokawa, his manager. Competent but flippant, Kurokawa always seems to pay extra attention to Shimano, whether it's teasing him to make him work harder or covering up for his mistakes, which of course drives Shimano crazy. So he has Kurokawa firmly blacklisted until he realizes that Kurokawa's private life isn't a bundle of roses and begins to sympathize...and how are you supposed to hate someone you sympathize with, anyway?

(Source: Vices & Devices)

Note: Includes two crossover chapters featuring the main couples from Ameiro Paradox and No Color.