A single-log bridge romance that unfolds as Seok Ji Won and Yoon Ji Won, who were born on the same day and with the same name and have been enemies for generations, reunite after 18 years.

Seok Ji Won is the executive director of Seokban Construction and the new chairman of Dokmok High School. Seok Ji Won is a naturally cheerful guy who has been able to do anything since he was young, whether it be studying or exercising. Seok Ji Won left his hometown and school due to family circumstances, but after returning home in glory as the chairman of a foundation, he meets his 'great rival' Yoon Ji Won who used to growl at him just by making eye contact, again after 18 years.

Yoon Ji Won is a physical education teacher at Dokmok High School's Creative Experience Club. Yoon Ji Won is a girl who earned the nickname 'Dokmok High School Mad Dog' during her school days. She cannot tolerate injustice and must find and correct bad habits and unreasonableness to feel better. As she experiences the ups and downs of life on her way to adulthood, the 'Mad Dog' inside her that had been quietly sleeping begins to emerge again when she reunites with Seok Ji Won.