Actually, Bi Xia had suspected more than once that Qin Zhan already knew her true identity.
Even though Bi Xia still didn't fully understand Qin Zhan's identity, just listening to Xu Renfei's words made it clear it was not simple. So Qin Zhan would have been able to find out about her with a bit of investigation. After all, if Xia Shi hadn't asked someone for help back then, it certainly wouldn't have been so easy to keep things under wraps.
But ever since Qin Zhan returned, he had only said things along those lines a few times and hadn't mentioned anything else.
Compared to her previous life, Bi Xia didn't fear that someone would find out her true identity now. After all, her cross-dressing as a man wasn't to hide any life-or-death secrets; it was just a product of the old-fashioned preference for boys over girls.
