In the depths of history, puzzling records were left in the Gwanghae year (1609) of the Joseon Dynasty.This year, a UFO appeared over the Gangneung Mountains. This incident not only caused a sensation at the time, but is still talked about by countless people today, more than 400 years later.

At that time, Xu Yihua, a fifteen-year-old girl in her prime, was preparing to go to her husband's house, accompanied by her servant.However, a trick of fate caused her to lose her future support in the tragic situation of becoming an outcast.What was even more unexpected to her was that on the way to her husband's house, a sudden strong wind knocked the sedan she was riding off the cliff.At this critical moment, time and space seemed to have stopped. A mysterious figure suddenly appeared and pulled the sedan that was about to fall into the abyss.

This mysterious figure is the alien who came to the earth with the UFO - Do Minjun.His appearance not only changed Xu Yihua's destiny, but also started her four hundred years of life on earth.Do Minjun, who has extraordinary vision and hearing, never looks old. In order to hide his true identity, his only friend, lawyer Jang Young-mok, declares his death every ten years and continues to live with a new identity.

Time flies, and the four hundred years of waiting are coming to an end.As a comet approaches, Do Minjun will return to his home star.At this moment, Seo Yihua has transformed into the popular modern national idol Cheon Songyi.Despite her beautiful appearance, Cheon Song Yi has a fatal weakness - lack of common sense.One of her unintentional mistakes on the Internet attracted a lot of abuse.

After moving, Cheon Song Yi and Do Min Joon became neighbors.The two met by chance in the elevator, but due to a misunderstanding, Qian Songyi mistook Do Minjun for a stalker.When being attacked on the Internet, Do Minjun's hearing made him intolerable to the noise next door.He went to remind Qian Songyi, but was rejected by the other party.Despite some self-blame, Do Minjun still sticks to his principles.

Cheon Song Yi's life has not been easy.She rarely appeared in university classes, triggering public criticism.The agency ordered her to return to class immediately.Coincidentally, Qian Songyi's class happened to be taught by Professor Do Minjun.After class, Qian Songyi tried to get close to Do Minjun, hoping to gain his favor, but Dou Minjun remained unmoved.

Cheon Song Yi's childhood sweetheart Lee Hwi Kyung has always been looking forward to her.After returning from the United States, he asked Qian Songyi to have dinner and proposed to her.However, Qian Songyi had something else in her heart.She has been looking for the benefactor who saved her twelve years ago, hoping to express her gratitude to him.

At the same time, Do Minjun also revealed to Jang Youngmok that he was about to leave the earth.He was filled with emotion and mentioned the little girl he saved twelve years ago. Her appearance was strikingly similar to the Xu Yihua he met when he first came to Earth.He longed to see her again before leaving, but he didn't know if this wish would come true.

The meeting again in the elevator brought Do Minjun and Qian Songyi to have more interactions.However, neither of them knew that the other person was exactly the person they had been looking for.Whether this fate spanning four hundred years can be consummated at the last moment has become the focus of everyone's attention.