Welcome to the N.H.K.(2004)

NHK ni Youkoso!

Sato Tatsuhiro is a drug-addled "hikikomori" (a Japanese shut-in) who thinks a sinister organization, NHK (Nihon Hikikomori Kyoukai), is the cause of all his problems! He falls in love with a girl, Misaki, who he thinks is trying to assassinate him, but doesn't know how to talk to her or if he can trust her. The more he stay in his house watching anime porn, reading manga and doing drugs, the harder it is for him to leave. Only Misaki can keep him from rotting away in his own apartment!

(Source: Tokyopop)