Hee-Do and Yi-Jin's Relationship Timeline Will Make You Root For Them Even Harder

"Twenty Five Twenty One" is a must-watch series for K-drama-lovers. The show tells the blossoming love story between an 18-year-old high school fencer named Na Hee-Do (Kim Tae-Ri) and a 22-year-old college dropout named Baek Yi-Jin (Nam Joo-Hyuk). They start out as friends, but their feelings gradually turn romantic the more they get to know one another. Since the series takes place over a number of years, it may be a little confusing to keep up with the couple's exact relationship timeline. To help you out, we've laid out all the most important events between the pair that help explain how Yi-Jin and Hee-Do went from friends to lovers.