Omega no Mukotori

Yoshiharu, an high-ranking Omega yakuza, is ordered by the head of the group to have a marriage interview with an Alpha from another group. But the Alpha, losing his patience with the wild Yoshiharu, forces him into heat with drugs. He's saved by his attendant Makoto, who he finds out is his fated partner. Yoshiharu is relieved that he's fated to the man who he trusts, but Makoto refuses to pair up with him?!

(Source: Kadokawa, translated)