Gu Wang Zaixia

When surgeon Su Kai Ji is suddenly transmigrated into the past, the first thing he notices is he is dressed in wedding clothes and being sent to the palace to be a consort?

On the wedding night, the emperor faces the beauty in front of him, and when he touches the flat chest underneath the bride's clothes, he feels his anger rise.

Emperor: I actually married a man?!
Su Kai Ji: Marry? I would never be the one on the bottom.

(Source: Kuaikan, translated)