Welcome to the N.H.K. (N・H・Kにようこそ! N.H.K. ni Yōkoso!?) adaptation produced by Gonzo and directed by Yusuke Yamamoto aired in Japan between July 9, 2006 and December 17, 2006. The series was coordinated by Satoru Nishizono, featured character design by Takahiko Yoshida, and the music was headed by Masao Fukuda.
(Source - Wiki).

A great series that I decided to try while waiting for the manga of Naruto: Shippuden to be released. The storyline is a little hard to explain, but I'll try.

It's about a guy, Satou Tatsuhiro, who believes the Japanese broadcasting company, N.H.K., is a conspiracy. Oh, he's also a 22 college dropout and is a hikikomori with an apparent Lolita complex. And his neighbor(I guess you could call him that), Yamazaki, has enlisted Satou in his attempt to create the greatest hentai game ever. And then the girl Misaki comes in, and invites him to participate in her "project". I don't wanna spoil the rest.

Welcome to the N.H.K. on Wikipedia.

Opening 1
Opening 2
Apparently, the 2nd opening is different somehow, but they sound the same to me.

Ending 1 (part of the vocals are by Kenji Otsuki >w<)
Ending 2

Genres: comedy, drama, psychological, romance
Themes: dark comedy, otaku
Episodes: 24
Age Rating: Older Teen
(Source - ANN)