Hyunjin was wearing a mask and he wasn't in his normal royal clothing. He wore a ragged outfit that he got for the town. He was hoping to see the gurl again as he waiys for her, at night, and at the edge of rhe walls where she enters the palace grounds.
He waits and waits for the past 20 minutes, he even yawned because of how bored he was waiting for her. Then, he sees her wearing all black clothing, he was very happy.