The Heroines Were Supposed to Stay Female, So Why Did They All Gender-Swap?

After suddenly transmigrating into the protagonist of a harem dating game, Song Ze is given a mission:

He must successfully romance every heroine in the game before he can return to the real world.

At first, Song Ze is thrilled.

A game full of beautiful girls? What could possibly go wrong?

But when it finally comes time to deepen those relationships and get intimate…

His nightmare begins.

W-Wait a second!

Why have all the girls I was supposed to romance turned into men?!