Netflix's [1] latest Korean romance drama, "Twenty-Five Twenty-One," [2] follows the budding friendship-turned-romance between Na Hee-Do (Kim Tae-ri) and Baek Yi-Jin (Nam Joo-Hyuk) [3] at different stages of their lives. The story jumps back and forth between the '90s and 2021, with most of the storyline taking place over the span of four years beginning in 1998 when Hee-Do is 16 and Yi-Jin is 20. (On the show, the characters' ages are referenced as 18 and 22, but this is because, in Korea, babies are considered one year old the day they're born, and then they get a year older on new year's, making their Korean age one or two years older than their international age.)

So, are these actors who portray high-schoolers in 1998 actually teenagers? Well, as is the case with most Gen-Z-focused teen dramas [4], the cast members of "Twenty-Five Twenty-One" are not necessarily the same age as their on-screen characters. But, considering how heavily the show focuses on age difference (I mean, the title is literally Yi-Jin and Hee-Do's ages), what may surprise you is how very different the actors' ages are from their characters behind the scenes.

For a complete rundown of just how close in age the cast is to their fictional characters on "Twenty-Five Twenty-One," [5] continue scrolling to find out the details.

How Old Is Kim Tae-Ri, aka Na Hee-Do? 31

Kim Tae-Ri's birthday is April 24, 1990, making her 31 years old — 15 years older than her character Hee-Do at the start of "Twenty-Five Twenty-One."

How Old Is Nam Joo-Hyuk, aka Baek Yi-Jin? 28

Yi-Jin being four years older than Hee-Do is a major aspect of "Twenty-Five Twenty-One"'s plot, but it's the opposite in real life. Nam Joo-Hyuk's birthday is on February 22, 1994, making him four years younger than Kim Tae-Ri in real life.

How Old Is Kim Hye-Eun, aka Yang Chan-Mi? 49

Kim Hye-Eun birthday is on March 1, 1973.