Kokushibo was muzan left hand man but he also hold deep feeling for him but he knows that it would never lead anyway since muzan was also an alpha and he's boss the demon king but one day when he enter the laboratory of muzan he saw him on the ground panting heavily as sweat scent was coming from him it was the scent of an omega......an omega in heat it in that moment that kokushibo discover that mean was an omega and he was in heat......