At eighteen, twin sisters Cheng Zhaoyun and Wen Muyu, separated since childhood, collide at university orientation and become enemies, yet end up in the same class and dorm. Accidentally discovering identical birthdays, birthmarks, and allergy histories, they confirm they are real sisters and join forces to expose Zhao Xian's rumors and framing. Facing emotional dilemmas—Ji Nanxian being soft and indecisive, and Gu Yu being domineering and controlling—the sisters swap identities for a displaced trip, experiencing firsthand the exhaustion and suffocation of each other's romantic relationships, leading both boyfriends to wake up and change. Re-exchanging identities at the airport, their parents unexpectedly reunite, and the sisters complete their growth, realizing that intimate relationships require equality and respect.