Keima is bishōjo gamer who is called "The Capturing God" on the Internet for his ability to capture any girl in any bishōjo game but does not like girls in real life. One day, he accidentally accepts a contract with the demoness Elsie to help her capture evil spirits that have escaped from hell and have hidden themselves in girls' hearts with the only way to force these spirits out is to make the girls fall in love with him. Keima angrily explains to Elsie that he doesn't like girls and his "capturing skills" only work in games but is shocked to learn that both of them will be killed by the magical collars on their necks if he breaks his contract, forcing him to comply. His first target is his classmate, Ayumi Takahara who is training for the upcoming track-and-field meet. Keima cheers her on by displaying banners using Elsie's magical raiment at the field everyday. While Ayumi is annoyed by his actions, Keima believes she will eventually get used to him and like him. After a confrontation with jealous seniors, Ayumi sprains her leg a day before the meet. However, Keima confronts her that night as he figured out that Ayumi faked her injury because her meeting with the seniors made her question her confidence. Keima consoles Ayumi and tells her to believe in herself, which makes her fall for Keima. They kiss when Ayumi keeps Keima from falling down the stairs, forcing the spirit out of her body and allowing Elsie to capture it. Ayumi wins the meet but loses all of her memories with Keima, though she blushes when Keima congratulates her. Much to his confusion, Elsie has transferred to his school, claiming to be his sister.

Keima confronts Elsie on why she’s still here and he still has the magic collar on his neck which the latter reveals that their contract is still not finish and the collar will only be removed until they capture all of the runaway spirits in the city. After meeting Keima’s mother, Mari, Elsie claims she is her “husband’s illegitimate child” which Mari snaps on her husband on the phone for his “infidelity” and allows Elsie to stay with them. Keima however, refuses to accept Elsie as his little sister as in his view, she doesn’t have the requirements that qualify her to be one which she tries to impress him albeit unsuccessfully. But upon hearing her story on wanting to be successful just like her older sister, Keima reluctantly accepts Elsie as his sister. During lunch at a popular food stall, Keima and Elsie find their next target, Mio Aoyama, a rich girl who proceeds to buy all of the yakisoba sandwiches. Keima believes she is an easy target as she has all the characteristics of a Tsundere, and a love confession might break her hard shell. However, the confession doesn’t work as planned, and Mio has her chauffeur beat Keima badly. As Keima and Elsie follow Mio to her home, they are surprised to learn Mio lives in a shabby apartment.

Keima and Elsie eavesdrop the conversation between Mio and her chauffeur and learn that the Aoyama’s family are no longer rich since her father died and Mio’s mother has been working hard to make ends meet. The chauffeur leaves in disgust after the prideful Mio refuses to stop pretending to be rich. Mio catches Keima snooping around and quickly goes back to her apartment. Since Keima is the only one to know her secret, he can use it to get closer with Mio. The next day, Keima becomes Mio new chauffeur by riding her to school in various elaborate bike carriages made by Elsie’s raiment. On the fifth day, Keima, tired of riding Mio current carriage, almost gets whipped by Mio who smiles but quickly reverts to her cold expression and goes home. Keima now decides the next stage of his plans by bringing her to a ball she was invited. At the ball, a dressed up Mio is angry to learn that Keima, now in a tuxedo, actually brought them at the mansion gardens but later teaches Keima how to dance. But after encountering a few rich people who look down on Mio’s current status, Keima finally confronts her that she should stop pretending to be rich. Even though she keeps the act up to keep her father’s memory alive, Keima convinces Mio that she should let go of the past and move on and live her on life for her father and Keima’s sake. Keima kisses Mio and the spirit from her body is captured by Elsie. The next day, Keima and Elsie meets Mio, who now loses her memories of Keima, who has a change of attitude and has accepted her family's status and burns incense for her late father. Yet she still acts prideful and blushes when she sees Keima.

Keima attempts to finish and get the heroine, Sora Asuka from the PFP Bishōjo game "Crayon". But the game has many bugs including one that loops a previous scene over and over again. No making things any better is the fact saving the game only crashes it and game company that made it is now bankrupt thus there are no patches to fix the game. In order to avoid the bug loop and finish the game, Keima forcefully enlists a reluctant Elsie to help record the choices that he made in the game. Elsie is at first confused on why Keima takes the game seriously but soon respect his dedication to help the girls in his games just like the girls he helps in real life. After many attempts, Keima finally manages to avoid the loop bug and goes to the next scene but unexpectedly gets into another bug, resolving him to try again much to Elsie's horror. A wikipedia article about "Crayon" reveals a rumor that someone managed to get the ending, hinting Keima was able to finish the game.

Elsie has become a fan of the popular teen idol, Kanon Nakagawa. However Keima shows no interest in her, explaining the flaws of idols in real life compare to video game idols. Unknown to both of them, Kanon just so happens to be a classmate of theirs and is coming back to school. When Kanon meets Keima on the school rooftop garden, she is shocked and depressed to learn Keima doesn’t know who she is and precedes to taze him repeatedly which at the same time Elsie detects an evil spirit inside Kanon and Keima’s next target. Kanon vows to make Keima acknowledge her and make him her fan by holding a private concert just for him but Keima ignores her and act cold to her. However Keima is purposely ignoring her as he believes it’s a trap as boys should be chasing girls, not the other way around. The next day, Kanon holds another concert for Keima which he ignores her again. Depressed, Kanon suddenly starts to disappear in front of Keima and Elsie.

Keima and Elsie realized that Kanon is actually turning invisible because of the spirit inside of her and he manages to stop Kanon from tazing him again by praising her song. As Keima sends Elsie to investigate, they learn Kanon was once a member of the pop idol group Citron before they disbanded and has never played any songs from her old band and Kanon's need for attention was the result of people not noticing her in the past. Keima later receive an email form Kanon and cheers up the depressed Kanon at her TV shoot. Kanon continues sending Keima an obsessive number of emails to visit her whenever she feels depressed. With the relationship going smoothly, Keima agrees to come to Kanon's Christmas Eve concert at Narusawa Seaside Hall. On the day of the concert, Kanon is nowhere to be found and Keima know it's time to go to the final stage of his plan.

As Kanon prepares for her concert, she soon gets second thoughts and fears she will mess up and be forgotten again which she turns invisible and leaves the stadium which sends the backstage staff looking for her. As the concert draws near, Keima finally finds Kanon at a nearby building. Keima knows why Kanon fears of being unnoticed but tell hers she shouldn’t seek people’s attention as proof as an idol as her hard work to become one was the proof all along. With his encouragement and her fans cheering for her, Kanon returns to the stadium, thanks Keima and kisses him which causes the spirit in her to leave and finally be captured by Elsie. As she about to go on stage, she learns her former bandmates from Citron, Yuri and Lime, have sent their congratulations to her for making this far and Kanon makes an amazing performance to the crowd. As Keima and Elsie leaves, he tell her his views on idols hasn’t change but views Kanon as a shining star.

This episode features 4 different perspectives happening on the same day. Elsie is angry that Keima called her useless for making his lunch despite "it" having bizarre ingredients that are still alive. After her friend Chihiro advices her on how to impress Keima, Elsie decides to make a strawberry cake for him. Unfortunately, she mistakenly uses ingredients from hell instead of normal ones which causes many accidents including releasing a Mandragon and blowing up the Home economics class. At the same time, Keima irks the english teacher Kodama who dislikes the fact Keima constantly play games in class, yet still manages to get a perfect score on his test. After getting into an argument with Keima over games and real life at PE class, Kodama is chased by the Mandragon. Meanwhile, the Mandragon arrives at the Katsuragi's residence where it drops Elsie's cake. Keima returns home and finds Elsie's cake and eats it out of guilt but get hit on the head with a vase by his mother who mistaken him for a thief due to the Mandragon, which is eaten by the "lunch" Elsie made earlier which then chases after Kodama, forcing him to cancel his meeting with Mrs Katsuragi. Elsie returns home, vowing to make another cake for Keima but he reveals he has tasted her cake and doesn't like sweets much to her chargin.

Keima orders Elsie to go to the school library to learn modern human history after learning her knowledge about human history is two centuries out of date. Instead, she becomes fascinated on a book about Firetrucks. When she looks for more books about Firetrucks, she ask one of the librarians, Shiori Shiomiya and detects a spirit inside of her. After bringing Keima to library, the two are amazed that Shiori manage to find 458 books related to Firetrucks. While Keima thinks Shiori used the library index, Shiori, deep in thought, wants to tell him she was able to find them as she remembered all the books she reads in the library but is too shy to speak up. The next day, Shiori arranges the books in the library and explain her love for books. Keima is aware how shy librarian girls like her are easy to figure out as they are a common character in games but unlike games where he can read what the character is thinking, finding out what Shiori thinks might be more harder. As Shiori removes some books to be dispose off and laments to herself about their fate, Keima helps her get one book she can't reach. Shiori tries to think on how to thank him but fumbles in her words while thanking him.

Shiori is embarrassed on what she said and tries to leave but when Keima comments on why books are useless nowadays, with much courage and anger, she verbally calls him stupid before quickly leaving. Keima later reveals to Elsie that he is purposely angering Shiori in order for her to speak up. Shiori laments on the fact that her shyness has prevented her to speak to people normally but decides she doesn’t need to communicate with people and the only things she need is her books. The next day, the Library committee has decided to add a Media room for the library. Shiori tries gives her opinion to the committee but is too shy to speak up. Later, she catches Keima writing in one of the library books which he justifies that he was making corrections and comments how books can’t instantly be corrected, angering Shiori and quietly shouting him an idiot before leaving. The next afternoon, she catches Keima doing it again only to realize he’s scribbling in his own book. In anger and confusion, she starts talking her inner thoughts out without realizing it until Keima points it out. The next day after that, Keima introduces himself to Shiori and talks about the library, now that she is speaking normally to him. With Shiori now speaking up, Keima decide it’s time to capture her heart after finding a Library notice to dispose books for the Media room.

Shiori locks herself and barricades the library to prevent the Library committee from disposing the library books for the Media room. As the committee tries to get inside, Shiori fall asleep and dreams how her love for books began until she is awoken by Keima who manages to enter the Library via a hole at the rooftop made by Elsie. Keima has come to support Shiori in her protest and stays close to her. The Library committee cuts the power to the library, surprising Shiori and causing the books around them to fall over them. As she hugs Keima, Shiori tells him only he understand her love for books and reasons for protecting them. However, Keima calls her liar and tells her she didn't barricade herself to protect her books but herself to the world. Keima knows she always wanted to talk to people but her fears of being misunderstood prevented that which is why she reads books as an escape from the real world. Troubled with this revelation, Shiori feels unsure on what to do until Keima drags her out of the rumble of books, tells her he'll be her support and kisses her, which releases the spirit. As the Library committee finally enters the library, Shiori finally speaks up for herself explain her reasons which the committee agrees to have a meeting about the dispose books. In the epilogue, Shiori feels like she has forgotten someone who was with her during her protest so she writes a story on what she remembers.

Due to helping Elsie capturing spirits, Keima has gather a large backlog of new games he hasn't played. So on Sunday, he plans to finish all the games in his room by playing 6 games at the same time by going into "God of Conquest Mode" which enables him to play multiple games at the same time with impressive speed, while still managing to logically make the right choices and enjoy each game individually but suffers from Burnout later. Elsie finds this impressive yet bewilder and leaves him alone. Realizing he cannot finish all of his game at this pace, Keima decides to up the ante by playing 24 games at once while in "God of Conquest Mode". Keima finally manages to finish all of his backlog games except one as he is too tired to continue but he soon start hallucinating where all of the game girls he captured encourage him not to give up. Rejuvenated, he finally finishes the last game and "follow" his game girls into the game world where they all sing and dance together. The episode ends with an announcement for the second season of the anime and a new character introduced.