Freshman Lin Man enters college from a small county, instilled by his mother Zhao Guilan with the mindset of saving whatever he can and taking advantage of anything free, resulting in terrible boundaries. After moving into Dorm 402, he free-loads daily necessities, free-loads food deliveries, secretly uses Tao Ye's mouse, and even uses his poor conditions to emotionally blackmail others. After being distanced by Shen Feng, Tao Ye, and Wen Chen, he instead feels that the others are petty, until he alone survives a bout of acute gastroenteritis and finally awakens: human favor is not calculated out, and the more petty advantages you take, the more expensive the things you lose become. Ultimately, he apologizes, makes compensation, shares chores, and wins back roommate friendship with sincere heart.