Omega disguises his origin in bed

From swe3t+moans BLScanslation:

A body that's never experienced heat has fallen into a trap of a first lust!

Shinomiya Rio, the third son of a major pharmaceutical company who been living a prosperous life has a secret . All Shinomiya's sons have been known to be born as Alphas, but only Rio has to live with hiding the fact that he is an Omega. He's been living his life knowing that the heat will come and therefore has to take an suppressant

But when the first lust comes...

Pixiv