The story of Caituan Sisters is very short, not sweet, sad or funny, and very boring.
Because my mother's surname is Sun, my sister's surname is Sun;
Because my father's surname is Zhang, my sister's surname is Zhang.
She is a bit fat, so I named her Zhang Xiaotuan;
I think I am a very good sister, so I named myself Sun Xiaocai.
Then I discovered the word "caishuan".