 If you liked
Omamori Himari
|
 ...then you might like
Date A Live
|
Similarities:
Same school, action, romance, ecchi and harem genre.
Same situation where the MC has no idea who he is.
Same situation where most of the harem would be living in the MC's house.
Dissimilarities:
One has an extra, mecha, sci-fi genre, while the other has supernatural as its extra genre.