Seems like an OVA, first episode released by yu:

http://a.scarywater.net/yu/Kyou_no_5...Byu%5D.torrent

"This one-volume manga by Sakuraba Koharu portrays the fifth grade in a... different light. The chapters ran in Young Magazine, a relatively small publication, and were then released in volume form, when it gained some cult following.

What makes this manga particularly unique is not it`s characters, which represent fairly run-of-the-mill manga personalities like those found in FLCL, Azumanga, and even Sister Princess--which should give you a pretty good idea of what does make this manga interesting: the perfect blend of school humor, plain ridiculousness, and raging sexual innuendo.

Ah, fifth grade like you wish you remembered it! "

http://www.5-2.jp/
http://www.animenewsnetwork.com/ency...me.php?id=6245
http://anidb.info/perl-bin/animedb.p...anime&aid=4241
http://www.animenfo.com/animetitle,3...o_go_no_n.html