Yoon Seojoon, the secretary of Lee Group's chairman, hides his advanced gastric cancer and underground boxer identity. After a drunken night with Chairman Lee Hyunwoo, Lee proposes a paid hookup arrangement, leading Yun to resign in heartbreak. However, he is persuaded to stay under three conditions and moves into Lee's home. Their secret relationship spirals out of control, complicated by love rival Kim Taehoon's schemes and the exposure of their kiss. Yun breaks up with Lee to protect him, but Lee publicly comes out upon learning of Yun's illness. As a new targeted drug offers hope for Yun's recovery, this sincere romance flourishes.