The art was good and the themes were unusual, but I gotta say that this manga is highly overrated. Almost 9/10? No way does it deserve that. Maybe because this mostly reached eclectic people who rate it highly, or maybe it's just trolls who are rating it high as a joke.
The pedo elements have been mentioned, but the stereotypical "bully that's in love" wasn't great either, especially because that character was an unrepentant jerk, and redeemed way too fast for basically no reason.
I'd say most people would rate it less than 5/10. Personally I'd give it a 4 or 3. I usually read things to the end just out of momentum and it's rare for me to drop anything, but I dropped this, and it takes a lot for me to drop something. I've finished stuff other people have rated like 6/10 or 7/10 even agreeing with that score so long as the content was inoffensive.
This manga does have offensive elements, but also I found it boring at times and with poor pacing and flow. I've read slop isekai and high school romance cliches slightly better than this, and that's saying something, because I HATE slop isekai and high school cliche series.