Sang-du is a 27-Old Gigolo and a Single Father Who Re-Enrolls at a High School for His Love. Sang-du is bereaved of his parents as a child and is raised by his uncle, a professional gigolo. Pal-lan, who falls for Sang-du, tricks him into thinking that her daughter Bo-ri is indeed his. Thus, Sang-du starts raising Bo-ri, thinking she is his daughter, forced into the life of a gigolo to make the ends meet, as she is constantly bedridden at a hospital for health problems. He, however, runs into Eun-hwan, his first love and the lover bound by fate, by chance. Determined not to lose her again, Sang-du goes so far as working as the gate security for a high school where she works as a math teacher. He even enrolls there as a 27-year old high school student, becoming her pupil. Eun-hwan, on the other hand, has a boyfriend who is a doctor, but cannot resist herself being drawn to Sang-du little by little. She tries to lure Sang-du away from resuming his \"career\" as a gigolo to pay for Bo-ri\'s hospital expenses as her health worsens...