Kang Baek Ho realizes that he is in love with his best friend, Ham Yi Seul, on the day of her wedding to another man. He travels back in time to various events of their lives hoping to change the outcome of their relationship. Will Baek Ho be able to change the course of their future?

Lee Shin is a university student majoring in modern music. He is the vocalist of band "The Stupid" and also plays the guitar. He is known for his good looks and his strong passion for music, but is in reality a cold person who is uninterested in non-music related things and has no dreams nor plans for the future. Shin initially likes Jung Yoon Soo, a dance professor at university, but this all changes when he meets Lee Kyu Won.Lee Kyu Won is a bright and outgoing student who was born into a prestigious family and is majoring in traditional Korean instruments, especially the gayageum. Kyu Won's grandfather, Lee Dong Gun, is one of the top 3 traditional musicians of his age, and his biggest wish is to have his grand-daughter trained to become a traditional music prodigy in 10 years' time. Trying to live up to her grandfather's expectations, Kyu Won immerses herself in training and becomes a university student who knows nothing besides traditional music. As Kyu Won's friends are fans of "The Stupid", she was forced to go to the band's concert with them. There she saw Lee Shin performing live, and is immediately captivated by him.

Lee Shin is a university student majoring in modern music. He is also the vocalist and guitarist of the band “The Stupid.” Shin is known for his good looks and strong passion for music, but in reality he is cold, lacks interest in anything unrelated to music and has neither dreams nor plans for the future. He initially likes Jung Yoon Soo, a dance professor at university, but this all changes when he meets Lee Kyu Won.Lee Kyu Won is a bright and outgoing student who was born into a prestigious family and is majoring in traditional Korean instruments, especially the gayageum. Kyu Won’s grandfather, Lee Dong Gun, is one of the top 3 traditional musicians of his age and his biggest wish is to see his granddaughter become a traditional music prodigy. Trying to live up to her grandfather’s expectations, Kyu Won immerses herself in training and becomes a university student who knows nothing outside of her studies. As her friends are fans of “The Stupid”, she was forced to go to the band’s concert with them. There she saw Lee Shin performing live, and is immediately captivated by him.

Kwon Oh Bok is a a 19-year-old young woman/orphan who refuses to give up her dream of becoming a top illustrator. Because she grew up poor (and is still struggling), she is extremely frugal, and maintains an optimistic outlook on things. Kwon Oh Bok has nothing that she can call her own in her life-time, not even the little room that she stays in. However, her hot temper will flares whenever she witness any injustice.

The four siblings in the Gung family were named after precious jewels: eldest daughter Bi Chwi (Jade), eldest son San Ho (Coral), second daughter Ryu Bi (Ruby), and the youngest son, Ho Bak (Amber). Like an assortment of beautiful gems, their colours may clash and their sharp edges chip away at each other. Using an analogy of a bowl of rice with assorted ingredients to illustrate the workings of a family, the key to a great dish is using the right balance of ingredients in order to create a good mixture. Assorted Gems tells the story of the different lives of the family members and how they learn from their clashes to find the perfect balance.