Trinity seven is similar to high school DxD in many ways (definitely less ecchi though) so if you enjoyed DxD you will love trinity seven.
The first episode is kinda a mind fuck but just stick with it they'll explain it all soon enough.
It was kinda refreshing to have a main character in a harem anime that respects boundaries, he teases but you know he'd never take it too far.
Season two hasn't been released yet, but the last episode wraps things up fairly well if you really need more I'd suggest the manga it's already far ahead of the anime and there are a few differences in the scenes.
Lastly stay away from Arin, she's mine!
