The Alpha's Bride -Love's Resonance-

Born as an Omega into a prestigious Alpha family, Iriya was raised to be a prouder and more superior being than an Alpha as the heir to the Kuou family. With his overwhelming beauty and charisma, Iriya is becoming the center of attention in high society. One night, he is invited, along with his childhood friend Keiki, to a party hosted by the prestigious Omega family, the Uryuus. There, an encounter with "him" causes a strange change in Iriya, who, even past the age of 18, had never experienced heat. His body begins to burn, releasing sweet pheromones—?! 

"If you want help, say it."

(Source: Taiyo Tosho, translated)