Hwi-Seong Lee, who was once a promising athlete with his gifted athletic abilities in high school, works part-time at a convenience store. One day, he is invited to an MMA event which eventually leads him to a new adventure. After visiting the Octagon for the first time, he feels overwhelmed by what he has just witnessed. How will his life change as he begins training, and will he rise to glory as an MMA fighter? (Source: WEBTOON, edited)