Hmmm... He wasn't a person from her world so there's two options: that witch transferred him as whole person with his body or she put him in someone's body who died in the same time while he was changing worlds (Like female lead). Only the author can confirm which theory is true ¯_(ツ)_/¯
But, in that case how did fl recognized him..... Well guess u r right only the author can confirm it...
Maybe she just felt it like intuition or something LOL. When i read spoiler about them meeting in her world i thought that she will recognize him after his choker but the manhwa's panel clearly shows that his neck is naked.
1 question... Did his face changed too..... !?????
Hope not.....