Proper Japanese Title: エイケン
Eiken is a manga series that focuses on the life of a highschool boy named Densuke Mifune, who after landing on a fellow class mate and old crush Chiharu Shinonome, is forced into the mysterious Eiken club populated by woman only, most of whom have really large enormous breasts. Eiken is a really fanservice- heavy manga, as we got not only barely covered up shot of woman's breasts but the garden variety of panty shots and much much more. As you can tell the theme of the series is fanservice with REALLY LARGE breasted woman. While the series is VERY Fanservicey, it doesn't go and flat out show nudity but they have alluded to it a number of times and show A LOT of details in certain areas that almost past for it like for example nipples poking through a bikini a little or panties forming a certain form. The manga has been translated into english but has been critizied as some of it is mistranslated and sometimes sounds engrish. The series has a anime of it's own but in the form of two episode OVAs that has also been dubbed and features some big voice actor names like Stephanine Sheh. Eiken also had itself a series of radio dramas as well. There are over 18 volumes of manga of eiken and it's been suggest that the series is actually a parody of Ecchi type animes/manga. The Manga and the anime are created by Seiji Matsuyama.
The Manga series is published by Akita Shotenand started in 2001 in an issue of Weekly Shōnen Championand ended in 2006 with as I said 18 volumes. It's publisher in english is Media Blasters.