I feel the same way, I can't really say I have any specially fond memories from High School (nor any miserable ones either) but there are some times that I look back and think that that time was the only time where I was close enough to adulthood to have some freedom but close enough to childhood that I could just goof off with no regrets. Once you graduate and go to college/work, it all just seems to fade away and unless you happen to be partnered up with something close to a soul-mate, your life won't be as bright as it was back then.
I was mostly a loner in highschool. I have a few friends but I doubt they were even being real friends. Highschool is a place for dramas, backstabbing and bullying. Yeah I don't want to re live highschool days. The one thing I regret is not confessing to my crush and taking graduation picture or even go to prom.
I feel nostalgic by reading this manga. Although I didn't really have many good memories with friends during my high school day, sometimes I missed those times... I feel like I wanted to go back time just to make sure that I do what I couldn't do back then; to make sure not to have regret like I have right now... Well, I recommended all of you to read this manga!! The story is simple but perfect!!! May all of you have a good nostalgic feeling!