There is a common Korean belief that anything plus nine (gu in Korean) is always "cursed" and brings about more hardship than usual, including the ninth year of every decade in one's life.
Gu Gwang Soo is 39 years old. He was once the brilliant PD of the nation's top live music program. But his fall from grace occurs when members of an indie band he'd cast drop their pants onstage and flash the entire country during a live broadcast (based on a real-life incident on MBC in 2005). Gwang Soo often thinks about his ex-girlfriend Joo Da In who suddenly broke up with him one day and left him heartbroken. When they meet again, she is a single mother whose life revolves around her young daughter.
Kang Jin Gu is 29 years old. He has two younger brothers, Min Gu and Dong Gu. Jin Gu is a tour planner for a large vacation travel agency, and he's popular, self-assured and carefree. Jin Gu falls into a one-sided love for the first time in his life when he confesses his feelings to his friend and co-worker Ma Se Young, but she tells him that she likes someone else, and he doesn't know how to deal with being friend zoned.
Kang Min Gu is 19 years old. He is a hot-tempered high school senior and judo athlete. Min Gu dreams of going to his dream college on a judo scholarship, which means giving his all to win a gold medal in his competitive matches. Min Gu keeps running into a cute but mysterious girl named Han Soo Ah all over town, and he decides that they're fated to be together. But Soo Ah has the entire district's high school boys swooning over her.
Kang Dong Gu is 9 years old. He is a child actor who got famous doing food commercials because of his healthy appetite. Dong Gu suddenly feels threatened when, for the first time ever, he loses a job to a new rival child actor and finds himself in a career slump. The precocious Dong Gu has also been secretly dating 8-year-old child actress Jang Baek Ji for the past two years, but she dumps him for his rival.
