Gokudou to Omega: Mukidashi no Katsuai.

Niikura Wakana is a struggling romance author whose latest challenge is to interview Tatara Kunimitsu, the irresistibly handsome and notoriously unattainable leader of the Koukyou Yakuza. Dubbed an alpha among alphas, Kunimitsu is an enigma wrapped in the allure of power. In her daring attempt to reach him, Wakana infiltrates a high-end club as a hostess, only to be ambushed by her first heat. As her dormant omega traits awaken, her pheromones wreak havoc, drawing unwanted attention her way. Just as peril closes in, the very man she came to see rescues her. Will Wakana be able to navigate her burning attraction to Kunimitsu while untangling the secrets of her own untamed heart?
(Source: Seven Seas Entertainment)
Note: Includes one extra chapter.