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Probably my all time favorite anime. Satou is a NEET (Not in Education, Employment or Training), spends his days sleeping, drinking and watching porn. He only leaves the house at night and only to go to the convenience store or have a smoke at the nearby park. One day a strange girl shows up, claiming she can "cure" him and make him into a functioning member of society. He wants none of it, so he pretends to already have a job as an erotic game designer. To back up this lie, he teams up with his neighbour (and former school mate) to create their own eroge.
Funny, dark, realistic and often depressing. One of three animes that I'd say actually deserves a 10/10 rating.
This trailer probably explains it better.