Satou Tatsuhiro's reclusive origins are explained - his anxieties lead him to believe that he is a victim of a conspiracy known as the NHK. When he meets a mysterious girl named Misaki Nakahara, she claims to be able to cure his hermitlike ways.
Misaki tries to convince Tatsuhiro to sign a contract with her, whereby he will be obligated to listen to her as she tries to ease him out of his reclusive lifestyle. Later, Tatsuhiro discovers that his neighbor is actually his high school friend, Kaoru Yamazaki, who is studying a media course in creating games.
Kaoru introduces Tatsuhiro to erotic video games, also known as eroge, and Tatsuhiro quickly becomes intrigued. Much to Kaoru's chagrin, Tatsuhiro ends up not doing any work on the game and instead, begins collecting pornographic pictures for "reference material".
Tatsuhiro, now a full-fledged otaku, is brought to Akihabara by Kaoru in hopes that it will inspire him to work, but he ends up going to maid cafes and spending all their money on otaku merchandise. By chance, Tatsuhiro bumps into his high school senior, Hitomi Kashiwa, and ends up having a drink with her.
Hitomi and Tatsuhiro's pasts are explored briefly. Tatsuhiro finally admits to Misaki that he is a recluse, and signs the contract. They have their first counseling session, and Tatsuhiro embarrasses Misaki with Freudian symbolism.
Tatsuhiro discovers from Misaki that Kaoru has a cute girlfriend in his media school. Despite his reclusive condition, Tatsuhiro ventures out to Kaoru's school to ascertain the truth. However, while the trip causes him another panic attack, he manages to find out the truth about Kaoru's supposed relationship.
Traumatized by his latest panic attack, Tatsuhiro refuses to leave his apartment. Under the guise of a summer flu, he gets Kaoru to buy him his daily necessities. Later, he is surprised by a phone call from his mother who tells him that she would like to visit him and discuss his future.
Kaoru is crushed when the girl he asks out for a fireworks festival turns him down and meanwhile, Tatsuhiro is tormented by his newfound feelings for Misaki, becoming so disturbed that he can't concentrate on writing a scenario.
Hitomi's feelings of isolation lead her to join a mysterious Internet group, where she makes up stories about being abused by her lover. Meanwhile Tatsuhiro and Kaoru finish making the game for Natsucomi and prepare for the trip. However, a phone call from Hitomi to Tatsuhiro causes changes to the plan.
The offline meeting turns out to be a suicide pact, and Tatsuhiro gets entangled in their scheme. Meanwhile, J?gasaki, Kaoru and Misaki are able to put together what is happening, and rush to save the group.
After recovering from the offline meeting, the group ends up getting checked into a hot spring, courtesy of Jogasaki, who also contacts each person's family. Misaki and Tatsuhiro are still on bad terms until they meet for one more meeting. Will it be their last one?
With his allowance having been cut, Tatsuhiro needs to get a job. He decides to join a MMORPG called Ultimate Fantasy to make some cash by selling game items for real money. His obsession with the RPG deters him to not do any work on his eroge scenario and he misses counseling sessions with Misaki.
Tatsuhiro meets up with Megumi Kobayashi, an old high school friend and his class representative. When he divulges to her that he's a recluse, she tells him she knows someone who can help cure his problem. She ends up whisking him off to an old dilapidated building where he finds himself listening to a sales pitch.
Realizing he has been tricked, Tatsuhiro meets with Kobayashi to call the deal off. Although at first, she seems willing to let him go, she soon manages to distract the rest of the group, eventually selling them another fake product which would allegedly help Tatsuhiro.
Tatsuhiro completes his chase to stop Misaki from committing suicide at the cliff where her mother killed herself years earlier. On the outlook of the cliff, in the snow, Misaki attempts suicide only to be stopped by Tatsuhiro.