Magikano, To LOVE-Ru Recommendations
Other than being a harem, both anime takes place in a normal city. Normal guy gets dragged by an energetic heroine and someone's out to assassinate him. The protagonist is also expected to be a great man someday. Oh, and the heroine is of royalty.
There are plenty of characters with similar personalities, like a tsundere, a sister who does all the cooking, cleaning, etc.
Finally, it deals with supernatural phenomenon (one is sci-fi, the other is magic).