A policeman discovers a love affair between his teenage daughter and her teacher which leads him back to an unsolved murder case he investigated 10 years ago.

A seemingly happy family gets rocked by the suicide of the 14-year-old daughter.

When Jo Gang-Ja attended high school, she was notorious for fighting. She gave birth to her daughter A-Ran in her late teens and became more responsible. Her daughter A-Ran is now a high school student, but A-Ran is bullied at school. Jo Gang-Ja decides to go back to high school to protect her daughter. Jo Gang-Ja becomes a high school student again.

Hong Ra On, disguises herself as a man and counsels men on dating. Due to a love letter she wrote for a client, she meets Lee Young – future Crown Prince Hyomyeong. Hong Ra On is unaware that he is the Crown Prince and Lee Young is unaware that Hong Ra On is a woman. The Crown Prince becomes interested in Hong Ra On. His eunuchs become aware of this and attempt to get Hong Ra On to become one of them.

Joong-ho is a dirty detective turned pimp in financial trouble as several of his girls have recently disappeared without clearing their debts. While trying to track them down, he finds a clue that the vanished girls were all called up by the same client whom one of his girls is meeting with right now.

The son of a North Korean spy decides to follow in his father’s footsteps to protect his little sister. After his father’s botched espionage mission, North Korean Myung-hoon and his young sister Hye-in are sent to a labor prison camp. In order to save his sister’s life, Myung-hoon volunteers to become a spy and infiltrates the South as a teenage defector. While attending high school in the South, he meets another girl named Hye-in, and rescues her when she comes under attack. South Korean Intelligence soon discover Myung-hoon’s activities and begin tracking him, all the while his own government sends a vicious assassin to eliminate him.

Lee Hyeong is a talented songwriter. He happens to connect people who are not good with love. Those include Hyeong-Gyeong who wants to become a singer, but she suffers from stage fright. Scully is a high school student. She helps Lee Hyeong’s spirit. Chan-Young is a colleague of Lee Hyeong and he likes Hyeong-Gyeong, but in vain.