While most anime features the occasional fanservice moment, only ecchi features storylines that are built around creating opportunities for fanservice. That doesn't mean that they don't tell a good story - many do - but the focus is squarely on showing off the character's assets, and putting them in titillating situations. There are plenty to choose from. He tries asking out an attractive woman who turns out to be a dangerous fallen angel who takes his life. When he's revived by Rias Gremory, the two team up to take down fallen angels and other dangerous beings.
Akemi’s Anime Blog : » Isekai no Seikishi Monogatari : AAW
The set-up is yet another insulting Tenchi Muyo spin-off not involving the actual Tenchi Muyo characters fans from the old days love. About the only way to make it more generic would be if he had amnesia. The series is certainly good looking; a wide range of memorably attractive character designs in the large harem cast, a decent amount of alternate-world architectural flavor, quality art, and relatively high-budget animation. And the world—which is either set in another time and place in the Photon universe, or borrows nearly every name in that show as well as the Ryo-ohki-substitute Koro designs—has plenty of interesting cultural twists, including a passably plausible reason for a large group of women being abnormally interested in one guy. So that helps.