At school, Chi Sui and Ji Xiwen are worlds apart. Chi Sui is the talk of the school, regularly placing in the top three on the grade rankings; Ji Xiwen is an unnoticed transfer student who keeps a low profile in class. No one knows: every Friday evening, they return to the same home. Later, when someone slips a love letter into Ji Xiwen's book, Chi Sui is furious. He corners her at home and warns, 'We can't have puppy love in this family, or else I'll—' Ji Xiwen presses her lips together and looks at him. 'Or else what?' Meeting the girl's clear bright eyes, he lowers his head, helpless. 'I'll be heartbroken.' Secret love is a sour, green apple.