“Twenty-Five Twenty-One” takes place from 1998 to 2021. In 1998, in a world that seems on the brink of disaster, two people aged 22 and 18 meet for the first time, but end up hurting each other at age 23 and 19. At 24 and 20, they learn to trust each other, and at age 25 and 21, they start to fall in love. Baek Yi Jin, a UBS sports reporter. After he becomes a reporter at age 23, he works as a makeup salesman and a bodyguard in order to stake out a story. He also lands a job as a sports reporter for the Asian Games. At the Asian Games, he meets a fencing athlete named Na Hee Do. Na Hee Do, who is selected for the national team after competing on her high school fencing team. She is a fencing prodigy who becomes a gold medalist..