Netflix's latest Korean romance drama, "Twenty-Five Twenty-One," follows the budding friendship-turned-romance between Na Hee-Do (Kim Tae-ri) and Baek Yi-Jin (Nam Joo-Hyuk) 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-focussed teen dramas, 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," continue scrolling to find out the details.