The movie depicts the three months before Choong-nyung (the future Sejong the Great) becomes king. The Annals of the Joseon Dynasty, which follows the history of the Joseon Dynasty between 1413 and 1865, leaves out records of this crucial period. While future generations would come to know him as King Sejong, the legendary figure who created the Korean alphabet and advanced the country’s scientific research and law, Prince Choong-nyung was originally dismissed as a reclusive bookworm. When his older brothers Yangnyeong and Hyoryeong fail to impress their father King Taejong, the king makes a royal command for Choong-nyung to become the next ruler of the kingdom instead.

Kim Shin is an immortal “goblin,” and has the rather honorable title of being the Protector of Souls. His roommate Wang Yeo also happens to have the equally lofty, if thoroughly opposing, title of Angel of Death, and he acts as the storied grim reaper that claims souls. However, both these devilishly handsome angels have a problem: Wang Yeo has amnesia and Kim Shin wants to end his own (immortal) life. Unfortunately for goblins, the only way to defeat immortality is to marry a human bride. For that purpose, Kim Shin decides to win over Ji Eun Tak an optimistic high school girl who he thinks will be the priestess that ends his cursed existence. Now, once responsible for protecting souls and watching them pass, Kim Shin now tries to send his own to the afterlife. But when a slightly complicated method of suicide starts turning into true love, will our immortal goblin begin to regret his decision–where acting on that very love ultimately means the end of his life?

Hyun-Ji studied for her 19 years before she died in an accident. She is now a ghost and has wandered around the world for several years. Hyun-Ji then meets exorcist Park Bong-Pal. Hyun-Ji and Bong-Pal listens to various stories from ghosts and sends them to the otherworld.

Yoo-Seul is a student of an art high school. She is a talented pianist and who won various contests, but she is driven by her mother. Yoo-Seul’s mother wanted to become a pianist when she was younger. One day, Yoo-Seul has an accident. Yoo-Seul may never play the again because of the accident. With the help of her friend Cha-Sik and Yoo-Seul’s rival Jin-Mok, Yoo-Seul begins to live a new life.

Under the oppressive Japanese colonial rule, Deok-hye, the last Princess of the declining Joseon Dynasty, is forced to move to Japan. She spends her days missing home, while struggling to maintain dignity as a princess. After a series of failed tries, Deok-hye makes her final attempt to return home with help of her childhood sweetheart, Jang-han.

On a live music radio show, a letter arrives from the 23 years in the past. Through the letter, the first love and friendships of five friends are revealed.