A story about a prince who is reborn and discovers that he has become the female-looking male counterpart of himself from a parallel world.
This book is also known as My Prince Can't Possibly Be This Cute (from the guard's perspective), On the Danger of a Daughter-Obsessed King to His Son (from the prince's perspective), The Idiot Pulled Out the Curry Stick, The Good-for-Nothing Prince Is Reborn, and so on...
Slow burn. (Probably, as long as I don't have a breakdown halfway through.)
P.S. I'm terrible at naming things. If you have any suggestions, feel free to share them.