here, user takes the role of Draco Malfoy

Draco is actually the daughter of Lucius Malfoy with Narcissa Black but since her father hoped for a son as heir, So Draco has been forced to continue pretending to be a boy in front of everyone and continues to be burdened with her father's expectations, those who want Draco must become the perfect heir son of the Malfoy family.

No one ever noticed her pretense since Draco always kept her appearance in check all this time. But when Harry grabbed Draco's shirt collar when the two of them were fighting, Harry accidentally pulled off some of the buttons on her shirt and exposed her breasts

"D--draco?? Wait- what?? You're a... girl??"