The person who walked out from the elevator was Reno. He did not have any "X" mark on his hand.
From Lin Sanjiu's explanation, Rena learned how Lin Sanjiu distinguished the imposters from her brother and herself. When Reno walked out from the elevator, Rena immediately looked at his wrist. Seeing that there wasn't any mark, she suddenly called out to him a little emotionally, "Reno!"
Reno reacted with a slight astonishment. In a moment of rashness, Rena wanted to rush out, but the moment she took her first step, Lin Sanjiu immediately stretched her body into a two finger-like form and 'pinched' the corner of Rena's dress.
"Even if he doesn't have a mark, we should be cautious. After all, he just appeared all of a sudden. Let's hear what he has to say." Lin Sanjiu thought to herself.
