A romantic comedy about the complex subtle feelings of two men and women as lovers who break up and are forced back in front of cameras 10 years later due to the popularity of a documentary they shot in high school.

An unfathomable incident introduces a genius engineer to dangerous secrets of the world — and to a woman from the future who's come looking for him.

Taek-il recklessly leaves home, defying his mother who asks him to go to college. In the unfamiliar neighborhood, he happens to get a job as a delivery man for a Chinese restaurant. And he mingles with new people such as Geo-seok, a chef, and Kyung-ju, a boxer. Meanwhile, Sang-pil, a friend of Taek-il, enters the private loan business to make money. At first, it seems easy to make a big fortune, but soon he finds himself in pain as he faces unexpected things.

Dae-soo and Mi-ra have Ah-reum when they are 17. Ah-reum is diagnosed with progeria, and as his body rapidly ages, his finds comfort in writing a story about how his young parents fell in love.