Episode 1
Jung Yu Jin is an outgoing, cheerful and popular 18-year-old girl at a high school in Chuan Chun. Her father Jung Xin Zhou has passed away, and she and her younger sister are raised by their mother. Yu Jin's family is close to Kim Sang Hyuk's family, and Yu Jin and Sang Hyuk grew up together. Sang Hyuk is an obedient student who is well liked by his classmates. He has been admiring Yu Jin all along. One day, Yu Jin and Sang Hyuk were late for school. Yu Jin managed to squeeze into the bus by herself, and fell asleep on the bus on the shoulder of Kang Joon Sang. Joon Sang is a quiet, talented student who has transferred to the school in Chuan Chun where Yu Jin studies, and he is there to look for his father. Joon Sang identified Kim Zhen Yu, a Mathematics Professor, as the person he is looking for. Zhen Yu is Sang Hyuk’s father. Joon Sang is hostile towards Sang Hyuk, and tried to compete with Sang Hyuk in every way...
Wu Choi Lim, who is in the same class as Yu Jin, is interested in Joon Sang. She made an open declaration that Joon Sang belonged to her. Joon Sang slipped into the University to attend Zhen Yu’s Mathematics lecture. The latter was duly impressed with Joon Sang's talent. Zhen Yu invited Joon Sang to go to his office to discuss mathematical problems with him after school regularly. At home, Joon Sang's mother, Kang Mei Xi (who was a pianist), asked why he wanted to be transferred to that school, and brought up the topic of Joon Sang's father. Mei Xi told Joon Sang that his father was dead, and he should go to US with her after her concerts ended.
Yu Jin and Joon Sang were late for school again. In order to avoid the fierce teacher who was guarding the front door, Yu Jin suggested that they could help each other to sneak into the school, via climbing over the wall. Joon Sang helped her up the wall and jumped over from the other side by himself easily. Yu Jin, who was left sitting on the wall, panicked and begged Joon Sang to...