An omega that hides his identity gets bitten by his alpha coworker. Thi shappen while the omega helps the drunk alpha home, as the omega goes into heat after sensing the alphas pheromones. He then hides the fact that they got bonded. The alpha seems more interested in him and gets to learn that the omega is not actually a beta but an omega and offers to help him on his heat days.
The omega accepts and they become sex friends. Turns out the alpha has had a crush on him since way before starting to work with him since he fell for the omega when the omega was an teacher assistant at his school.
Usotsuki Omega ha Sakaraenai