Tatsumi is a virus researcher in the General Division who has a growing problem; his body releases Estrus pheromones and needs to have sex to calm his heat... but Tatsumi has haphephobia. Suou, a man who joined the General Division due to an incident caused by Tatsumi's experiment, is the perfect match for Tatsumi's heat every night - and he can't hold back his desire to monopolize him. The Omega origin story of the estrus virus!