The plot synopsis of "Shang Dao goes to school"

Sang Dao (played by Jung Ji-hoon/Rain) lost his parents when he was young. His uncle brought him to a wealthy family, and that family adopted him. Eun Huan (played by Kong Hyo Jin) is Sang Do's first love. Every morning, she would stand in front of Shang Dao's house and shout: Shang Dao, let's go to school! At that young age, innocent feelings grew with age. Once, there was an accident at Yinhuan's home, and Shangdao was imprisoned for helping Yinhuan. After being released from prison, Shang Dao discovered that Yin Huan had disappeared, and his adoptive parents also abandoned him and immigrated to the United States.

From then on, Shangdao lived a lonely and helpless life. By chance, she met Sara (played by Hong Soo Hyun), who was also an orphan. In order to keep Sang Dao, Sara lied that Baoli (Choi Min Joo) was the child of her and Sang Dao. Baoli, who was born prematurely, has been suffering from illnesses since childhood. In order to pay for her daughter's expensive medical expenses, Shangdao had no choice but to become a gigolo and make a living by defrauding wealthy women.

By chance, Shang Dao meets his former lover Yin Huan again. Shang Dao found that he still loved Yin Huan deeply and launched a passionate pursuit of her. In order to get close to Yinhuan, he went to the school where Yinhuan was located to work as a security guard, and later became an older student in Yinhuan's class. When Yin Huan was finally moved by Shang Dao and planned to accept him, he was worried about Baoli who was seriously ill and did not want to drag Yin Huan down. Sarah, who was unwilling to lose Shang Dao, also obstructed their union in every possible way. Finally, after going through hardships, the lovers finally came together.