First thing to note is that although Hi School is in the title, this is not a school drama. Plot sounds very dubious but really works quite well, VERY funny, very inventive and a real good satire on corporate managers and their sycophantic making up to the boss, stabbing-in-the-back/downtrodden subordinates, Hyuk is really convincing in his role. Don't know why reviewer above thinks there's no villain - there is [well, for a lot of it - in fact two] and how could the interest be sustained otherwise? Jo Han Chul is also very funny in his OTT neurotic team leader role, I think some people are really like that in companies. Love angle becomes too heavy, ep.11 very complicated, not so funny, I lost interest a bit in the middle [I think you say it "sagged"] and it was on hold for a while, but really picks up after that and I positively wanted to watch it. Lee Soo Hyuk looks much better with a schoolboy haircut. Lots of feel good in the end, but deduct a point for loss of interest in middle which may have stopped me finishing it. Music so-so, ok for this show. Not one I think I'd watch again.