It's normal...
First of all, the heroine Bian Shi is a girl in fifth grade, about 10 years old. Born on May 28
Second, the male protagonist (not actually the male protagonist), Tang Hang, entered fifth grade one year late.
Because my birthday is in November, I only entered the first grade when I was 7 years old.
Next are the secondary characters, mother, father and so on.
Dark modern fairy tale.