Boku to Kanojo no XXX
(Sadly no daddicts, or asianwiki page for it)
So summary: Two highschool students, a rough tomboy girl and a gentle sensitive boy, end up having their bodies switched thanks to the girls scientific, and irresponsible, grandfather. This short 2005 series chronicles their hijinks, torments, and pseudo sexual exploration.
The series was cute, nothing overly exciting, and as I sit here writing this, I'm not too sure I recommend it. The manga was worlds better, and the series mainly tried to play off the sexual tension, and innuendo, then try to really tell any story.
This was a hardsub that I pulled from daddicts way back when. If you're interested I can email jewelchan, who subbed it, for permission to post it to mega and allow for download.