I absolutely loved this series. Really wish there was more.

If you want a great (but a tear jerker and not yuri) manga about the problem of bullying in Japan, I highly recommend the hugely acclaimed and widely discussed oneshot Koe No Katachi. http://www.mangapark.com/manga/koe-no-katachi

And here's a download from Futari Wa Pretty Anon.

http://prettyanonymo.us/?p=3110

A really nice read, a deserving winner of the 80th Weekly Shounen Magazine Newbie Best Mangaka Award, and if this is a accurate portrayal of bullying in japanese schools, than it's definitely a serious problem.

Naaah no Yuri no live!

I hated reading that. It was a nice story but it hit a little too close for me.