At the age of 17, Yuchen was in his first year of high school and met 19-year-old Yumo, who was the "tutor sister";
At the age of 19, when Yuchen was a freshman, he met Yumo again, this time Yumo was his "sister";
At the age of 22, Yuchen was a senior and met Yumo again. This time Yumo was "Yumo".
Conception: