The story of Tang Jianan and Liu Xu begins on the university campus, which is lined with green trees, teaching buildings and libraries, and is a paradise for students to learn and grow. Inside and outside this vibrant campus, a youthful love song about love at first sight and regretful misses is about to be staged.
Tang Jianan is fair-skinned and handsome, a man of the hour on the basketball court. As he nears graduation, he is Liu Xu's Japanese class substitute teacher. He has a delicate and tender heart hidden deep in his heart and does not show it to others easily. Liu Xu has a quirky personality. He was attracted by Tang Jianan's mystery when they first met him, but he also felt heartache and loss amidst constant misunderstandings.
The two people who were extremely attracted to each other ended up missing each other due to family changes and various misunderstandings. When they reunited many years later, they only said "Long time no see".
Concept: Youth is a regret.