When Lai Mingjie heard that they would be opening that secret treasury that even he—the very demon it was attributed to—didn't know about, he grew very interested in it. Even if he was reaching his limit and would pretty much want to fool around with Xu Rouguang at night, he decided to follow them to where it should be.
The swim was long and tiring, but Xu Rouguang's wind was keeping pressure off of everyone so they only needed to actually swim. Lai Mingjie could just enter a semi-material form and get away with a lot of things. He followed them until they reached the blockade.
From inside, he could feel multiple things that he had never seen in a very long while. Books, weapons, and whatnots that he collected but couldn't use were all here apparently. So when he realized that Shui Ying wasn't willing to show it off to the humans, just letting them know that something was indeed there; Lai Mingjie opened it by force.
