Denpa-teki na Kanojo, Denpa Onna to Seishun Otoko Recommendations
Crazy girls harem for our hero. Both got industry-leading lengthy name. Not to mention that it's basically harem spiced with stuffs don't belong to romance, violence and aliens for example.
The OVA one is full of girls who are, by all social definition, eastern or western, violent. All girls take the liking of the male lead, some want to get along, plenty want him dead.
The Shaft-made one is sci-fi flavored love comedy. Girls are non-violent, but extra-strange nonetheless.
Both fit for the you who are bored with common harem setting without blood and aliens, with Denpa Onna give you some makeshift sci-fi and Denpa
They both have girls who believe in something made believe and the guy has to go certain lengths to deal with them. However, Denpa Onna to Seishun Otoko is like the more. . . childish one. I mean, don't get me wrong, Denpa Onna is still fantastic and has a handful of mature parts, but Denpa teki na Kanojo is. . . practically 100% mature. However, both are pretty damn good so i'd recommend both.