How did Dayong see Xiaoyu in The Unspeakable Secret?

Actually, it is. It has been raining for twenty years, and the first person to see it can see it. For example, Xiao Lun was the first person I met twenty years after Xiao Yuqing came, so only Xiao Lun could meet Xiao Yuqing that day. I wonder if the landlord has noticed. Xiaoyu carefully counted the steps from the piano room to Xiao Lun's classroom window, so that she could see Xiao Lun for the first time every time she came here twenty years later. Once Yiqing was sitting in Xiao Lun's chair, so there was a scene of Xiao Yu and Yiqing chatting while playing the piano in Xiao Lun that day. Didn't Xiaoyu come to class for fifteen days? Maybe the first person I meet every time is not Xiao Lun. Xiao Lun and Yi Qing kissed that day. Dayong was the first person Xiaoyu saw, so only Dayong could see her that day. Xiaoyu ran away and hid in another piano room. Because Xiao Lun couldn't see Xiao Yu that day, Xiao Lun didn't see Xiao Yu looking into the piano room where Xiao Yu was hiding. Besides, Dayong was in this school twenty years ago. He knew Xiaoyu twenty years ago, so he knew that Xiaoyu was called Xiaoyu (? ? ), will shout "light rain ran away".

I don't know how to explain this, has the landlord made it clear ~ ~ ~ ~