If you want a story with large bust fanservice that never ends, both the manga and anime of this will have you covered.
If you want a meaningful plot of any sort, don't bother.
Of the two, the anime is a brief OVA that is honest enough to pretend the plot doesn't really matter, since it's too brief to adapt anything substance from the manga, mostly relying on an endless parade of fanservice to keep you entertained.
The manga has slightly more plot, but it's mostly about a doormat of a guy meets girl plot, gets invited to be the token male of a school club of other idiotically busty women (including an 11 year old with beach balls for breasts, which is so ridiculous in a bad way it's actually rather offensive), and mostly winds up getting hurt quite a bit in the name of what passes for comedy.
The wasted potential would be in the lame use of the World of Buxom trope. You could have a comedy that also showed what a world where being impossibly busty is the norm and how that would affect the women in that world, which would add a nice bit of speculative commentary to the work, and would have definitely given Eiken a little more plot than the watery soup of a plot it had, but nope, the large boobs are little more than just a neverending shameless pandering to the lowest common denominator, and while one could argue this is a parody of other ecchi works, its too dependent on its own shameless cheesecake to be self aware enough to lampshade the absurdity.
In short, I don't recommend this at all, even if pointless fanservice is your thing.