Ore ga Suki nara Hizamazuke

The main office of Toto Daiichi Bank is a place where the elite compete for the top jobs. Matsuda works on the 21st floor in the Sales Department. Kato, his former classmate, is his main rival. Whether it is work, women, or popularity, Whenever he thinks he has won, the next moment, he finds Kato looking down on him in disdain. One night, while working late, Matsuda discovers that his girlfriend is cheating on him. He is frustrated because his pride has been hurt, when Kato kisses him out of the blue and says, "You have bad taste in women, you should go with me instead."

(Source: b's-garden, translated)

Note: Chapter count includes 1 extra chapter.