"Welcome to the N.H.K." is based on a novel by Takimoto Tatsuhiko, turned into a manga with illustration by Ooiwa Kenji.
Satou-kun, a socially withdrawn loner, barricades himself in his apartment, subsiting on a meagre allowance sent by his parents, only venturing to the outside world to buy food under cover of darkness. One day, afraid he might miss the utility person, he opens the door to find a cute, mysterious girl, accompanying an elderly religious solicitor.
Through what seems to be a chain of coincidences, the girl, Misaki-chan, enters the life of Satou-kun, and promises him that she will cure him of his anti-social condition, provided that he follows the rules that she sets out for him.
What follows is a story that takes Satou-kun from a desperate attempt at creating a galge computer game, to unwittingly joining a suicide cult, to participating in a pyramid scheme, to immersing himself in a MMORPG, along the way touching upon everything between hikikomori and otaku culture, existentialism, solipsism, theology, suicide, sacrifice and love.