Starting off, I just wanna say that Blue Birthday improved a lot as it progressed, the plot became more and more unpredictable as it goes, and each episode managed to leave us in suspense, curious about what's going to happen next. Yeri and Hongseok did great as Ha Rin and Seo Jun, considering they're both new in acting. I'm gonna be honest in saying that their acting bothered me a little in the beginning, but seeing as they got better throughout the episodes, I'm just gonna assume that they haven't quite immersed themselves in their characters at the beginning. Personally, I think that Hongseok really fit Seo Jun's role. He managed to pull off that first love kind of vibe well. Considering my initial response to the first few episodes, it's surprising how I'm finishing this drama with many positive thoughts about it. So if you're having doubts about starting this drama or continuing on, I suggest you give it a shot. Who knows ? It just might surprise you as it did me.