College student Xu Ning works part-time to save money to buy an expensive face cream, allowing herself to use it only four times, but her roommate Tang Rui uses it to rub her feet, while Zhou Qian and He Yuan also casually take her skincare products as public items. Xu Ning proposes asking before borrowing and locking up personal items, but Zhou Qian pressures her using old sentiments and the name of sharing. Joint purchase advance payments are altered to decorations without authorization, and she is misunderstood by acquaintances. Using transfer records and the boundary of a sentence "only borrow one pump", Xu Ning recovers the debt and clarifies the facts. The roommates gradually learn to respect, and she finally finishes an entire jar of face cream by herself.