Drama tells the story of Ko Dong-Man and Choi Ae-Ra. In their school days, Ko Dong-Man took part in taekwondo. Now, he makes a living by working as a contract employee and also goes after the UFC title. Choi Ae-Ra hoped to become an announcer, but she gave up her dream. Now, she works at the information desk of a department store.

“LUCA" is based on Charles Darwin’s proposition that all species of life have descended over time from common ancestors. (LUCA stands for "last universal common ancestor.")