This story mainly revolves around Moo, a boy at his last year of high school who dreams of becoming an idol. Since this dream is making him neglect his studies, however, his mother decides to make him go study in the countryside for his last few months of high school. She also forbids him from following his dream at least until he graduates and gets a place at a university.
In an unfamiliar place, lost and alone, Moo quickly grows attached to Kang, who works at a restaurant near his apartment building and is kind and helpful to him from the start.

I will never get tired of saying this: the content of the story matters, but the way it is told matters way more, and I believe that Only Boo is just another proof of that. The story is simple and it's mainly about Moo's crush for Kang and his continuous efforts to win his heart, all while he still chases his dream of becoming an idol and tries to keep up with his exams. While the details about Moo's new life are little, it's clear that they were crafted properly: I've never felt like anything during the story was useless or out of place. There were parts of the story that I wish were showed more, mainly Kang's passion for art and his trauma, which I've felt were introduced and then resolved too quickly and easily, but the story flows very nicely as it is and I can't say I missed that aspect too much while watching.

Among the cast members, Keen is with no doubt the one who shone the brightest from the beginning to the end. He portrayed a very cheerful and lively Moo and his facial expressions and body language were on point all the time. It was also a relief to notice that he's actually very good at singing and dancing, making him just perfect for the role. Unfortunately I can't bring myself to say the same for Sea: I don't know if it was just because of the character, because Keen looked so alive in comparison, or if it's just how Sea is; what I know is that he looked very stiff to me all the time. I had the impression that their couple worked so well because Keen did most of the work to make it believable on camera, rather than for their efforts combined.
The secondary characters all contributed to the general atmosphere of the series, making it a true delight to watch. Moo's new friends Potae and Payos, Kang's best friend Neth, even the principal created both hilarious and heartwarming moments that contributed to make me devour the show in less than three days. Big props to Aun and Ashi for their chemistry as the secondary couple of the story, although I didn't feel as captivated by them as I was by the main couple.

The OST is very good; it features multiple songs from different GMM artists in the first episodes, and then introduces new songs by Keen that I found very beautiful. Believe it or not, nobody plays the guitar in this series!
The production was very good as well. I really liked the bright colors and the bright environment, which definitely contributed to make the story feel warmer and cuter overall.

I highly recommend watching this. It's not a cinematic masterpiece, but it's so cute and heartwarming that I believe it will stay in my memory for a very long time.