You've probably heard of Nana, so no need to introduce Ai Yazawa. Honestly, this is one of the very few mangas that captures the instant of happiness just as well as the more negative emotions. The artwork is also beautiful. As far as "high school shojo" go, this one is just exceptional - so much that all the other ones I've read left an aftertaste of "something's missing". Many scenes will give you that special feeling you had, at the end of a summer high school day, when it's warm and you're hanging out with your friends and it's golden hour. I've read it multipletimes in the 10 years since I've bought it and it's never lost its charm.