Imitation Mate

Tsukasa is the ideal alpha: he was raised in an elite family and now works in his father's company. One day, he happens to meet Yoshiki, a fellow alpha and former high school classmate, who he once saw as a rival. However, he is surprised to discover that the aloof Yoshiki is living a carefree, unprofessional life that is completely atypical for an alpha. They go out drinking to celebrate their reunion, and Yoshiki has a few too many, prompting Tsukasa to help him get home. That's when Yoshiki seizes the chance to entice Tsukasa: "Being with another alpha can be fun, too." Even though he is against it at first, Tsukasa eventually gives in to the frenzy of pleasure and gets carried away in a relationship that isn't just a one-time thing. He figures that he can stop this kind of infertile relationship anytime he wants...That is, until he notices changes within his body... (Source: Renta!)