Hiding in the East Palace, the prince turned out to be a girl!

【System + Sign-in + Hiding + Playing Pigs and Eating Tigers + Upgrade and Development】
The protagonist Xiao Fan was originally a newly graduated Chinese major college student, whose soul traveled to a newly dead baby in another world.
He became a scholar at the age of thirteen, passed the imperial examination at the age of sixteen, and became a tribute scholar at the age of seventeen. Then he was selected by the prince and became the prince's tutor.
Prince Qin Xuan had an engagement with Jiang Yuli, the granddaughter of the general who guarded the country. As the wedding was approaching, Prince Qin Xuan found Xiao Fan and asked him to take his place in the bridal chamber.
Xiao Fan was shocked. Cuckolded Prince, are you going to die?
The prince had no choice but to say that he was a woman. Her real name was Qin Xuan, and she was peerless.
If he didn't agree after knowing the secret, he would die, so Xiao Fan had to agree.
At the critical moment, the system finally awakened. He had the Supreme Sign-in System, which claimed that there was nothing that could not be signed in.
"System, can I sign in to get another system?"
"System, can I sign in to get a universe?"