Lee Jin-ha, who has become the college student she dreamed of, starts working part-time at a bar to earn some pocket money. One day, the kendo club that her classmate belongs to visits the bar, which is bustling with customers. Jin-ha, caught off guard by her classmate's request, ends up participating in the kendo club's gathering and meets the charming senior, Do Ha-jin. The atmosphere of the club's meeting becomes increasingly lively, leading to a drinking game. However, this senior seems to be targeting only her? In response to Ha-jin's playful provocations, which seem to be aimed solely at her, Jin-ha also decides to fight back. Their meeting, which started off on the wrong foot, comes to an end, and a few days later, Jin-ha and Ha-jin run into each other again in the same lecture. Unexpectedly, they are assigned to the same group for a project. As they work together, they become friends and even join the kendo club together. After that, when Ha-jin graduates first, their close relationship gradually fades away. Three years later, Jin-ha also graduates from college and gets a job at a solid company. Her years at the company pass smoothly without any issues. However, one day, a departmental reorganization occurs at her workplace, and her new team leader turns out to be her senior, Do Ha-jin, with whom she had been playfully bickering during college. The time they spent apart seems insignificant as they meet again, bickering and teasing each other, but soon Ha-jin's attitude begins to strangely irritate Jin-ha...