Sora no Otoshimono Forte

Angeloids = Persocoms 

-Both main characters are quite weak -Both leads have childhood's friends who like them -Both characters get beaten up to a pulp :] -Both leads girls live with them -Both anime girls are usually stronger than guy -Both guys are oblivious for the fact that the girls like them -Same type of humor -Lots of other things 

Sora has three angeloids hanging around the main character instead of a Necromancer, Mahou Shoujo, and Vampire Ninja.  

Both sequels from their respective first seasons. Both were released in October 2010. both continues the misadventures of the indecisive main character (Tomoki / Rito) and his supernatural pink haired girl (Ikaros / Lala). Involving new characters, both series have a sexy funny girl (Astrea / Momo), who likes to fool around and make fun of the rest, specially the Tsundere girl (Nymph / Nana), who secretly loves the main character. 

in both series the main is what you would consider as a pervert. in both series the main character appears useless , and is therefore often protected by the girls around him creating a harem setting. The fantasy and supernatural genre is very prominent in both these series , if you like on you'll probably enjoy the other  

Both are action ecchi series with a perverted main character who have tons of girls around him. Otoshimono deals with angels while Hagure deals with heroes coming back from alternate worlds. Otoshimono's main character isn't a badass like Hagure's though. 

Both are hilarious and random shows with some ecchi. Just don't expect any complex plots from these and you will surely enjoy the experience (unless ecchi is not your thing). 

I was pondering how Nymph looks so much like Sasami from Tenchi Muyo with her blue haired twin-tails, but that got me thinking of other resemblances to the classic anime harem: *SPOILERS* Tomoki = Tenchi (although Tomoki's a much bigger perv, both are heavily influenced by their grandfather) Sohara = Ryoko (childhood friend, first one to have a crush, could kill him with a single slash) / Kiyone (ambitious, gets upset at stupidity) Ikaros = Ryo-Ohki (pet-class, secretly powerful, adored by all, loves watermelon/carrots, can assume a spaceship form during combat) Mikako = Ayeka (purple-haired president/princess with the smug laugh) Suhara = Washu (eccentric scientist/explorer) Astraea = Mihoshi (ditzy blonde, though Mihoshi preceded the boob-service trend) Tomoko = Pretty Sammy (magical girl parody) Master of Synapse = Kagato (main bad guy) Daedalus = Achika Masaki (mom figure) Chaos = Yugi in Tenchi in Tokyo (little girl antagonist) Hiyori (movie) = Sakuya in Tenchi in Tokyo (later love interest revealed to be an alien) Harpies = Azaka and Kamidaze (alien guardians, ok that's a stretch) Synapse Monolith = Jurai Tree (icons from the other world) read more 

Sakurai Tomoki and Shaka Virgo have similar special techniques, both shows full of manliness and epic flashbacks. 

Both series are action ecchi and have perverted main characters who have a ton of girls in love with him. Otoshimono involves angel while DxD involves demons. Also, DxD's main character is a badass while Otoshimono's is useless in a fight.