Ore no imouto ga konna ni kawaii wake ga nai

A party is held for Kyosuke at his new apartment and Kirino arrives there just to find Manami, and despite her animosity towards her brother's classmate, she decides to put it aside for his sake. Ayase, Ruri, Saori and Kanako also attend the party, but chaos ensues when they start arguing about who among them should take care of Kyosuke as he prepares himself for the mock exams and Kirino settles it by appointing Ayase to the task. The mock exams come and thanks to Ayase's support, Kyosuke manages to earn an A grade and the right to return home. As he is preparing to move back, Ayase confesses her feelings for him, but he politely declines, revealing that he is already in love with someone else. Instead of kicking him like she usually does, Ayase kisses Kyosuke on his cheek and bids farewell to him.

After hearing about Kyosuke and Ruri's breakup, Ayase becomes irritated that it had nothing to do with her. Nonetheless, she asks Kyosuke to take up his 'manager' role once more as she asked to help out at a Meruru concert that Kanako and Bridget are participating in. After hearing Kirino will be unable to attend the concert due to her work schedule, he borrows a bike from Kouki and rushes over to pick her up. After managing to get to the concert in time for ClariS to perform, Kirino feels thankful towards Kyosuke for his efforts.

While being treated by Kirino after getting his face wounded by some reason, Kyosuke reveals to her that he and Ruri decided to start dating, and much to his surprise, she does not complain about it. In their first date, Ruri wears a special cosplay she designed specially for the occasion, much to Kyosuke's astonishment. As the day pass, Ruri shows more about her tastes and preferances to Kyosuke and she reveals that it was written in a special guidebook made by her in order to attain her wish, which according to her is to have him and Kirino get on terms with each other. Despite not understanding the meaning behind her plans, he agrees to help her with it. The two then spends the following days hanging together in his and her houses, with Kyosuke being introduced to her younger sisters in the occasion, and by the end of summer break, they go to a festival together.

The boy is introduced to be Kouki Mikagami, a designer from Misaki's company who, to Kirino's surprise, is also an otaku. Later, after Kyosuke explains the 'fake date' scenario to Ayase and asks her opinion on whether Kirino has a boyfriend, things get tense at the after-party when Kirino witnesses Ruri assumedly confessing to Kyosuke. Irritated, Kirino announces that Kouki is her boyfriend, pushing Ruri to leave and angering Kyosuke with her remarks. Later, Kyosuke becomes irritated when Kirino invites Kouki to their house, receiving an angered slap from her when he shows his distaste. After speaking with a drunken Daisuke, Kyosuke grovels before Kirino, explaining his honest feelings and stating he won't allow Kirino to date Kouki until he proves himself worthy. Kirino eventually breaks down and reveals she lied about dating Kouki because she was jealous of Kyosuke and Ruri, with Kouki agreeing to pretend to be her boyfriend.

Kirino's track rival from her time in America, Ria Hagry, comes to Japan and stays over at her house. Kirino feels a bit protective of her, often dishing out punishment at Kyosuke following every little misunderstanding. Kirino and Kyosuke take Ria to Akihabara to show her Kirino's various hobbies. Afterwards, Ria challenges Kirino to a race, understanding what drove her to beat her back in America. Although Kyosuke cheers Kirino on, Ria manages to beat her, feeling proud of getting her revenge. Before leaving Japan, Ria hints to Kyosuke that he is the reason Kirino works so hard, though Kyosuke is a bit skeptical of that. After Ria leaves, Kirino brings up an odd request for Kyosuke to be her 'boyfriend'.

Feeling frustrated that Kirino is ignoring her in favour of a popular mobile game called Love Touch that lets you exchange texts with virtual girls, Ayase asks Kyosuke to do something about it. After Kyosuke brings it up to Kirino, she gives him Love Touch to avoid being tempted by it, only for Kyosuke to end up becoming addicted himself. As Ayase becomes angered upon learning of this from Manami, Kyosuke attempts to explain how the game's heroine is similar to Ayase. He suggests imitating the heroine to better hold Kirino's interest, but this is soon met with violent backlash from Ayase when dubious phrases are brought up. After Ayase goes to Manami for advice, Kyosuke is shown the error of his ways when Ayase decides to imitate the game's yandere route in front of Kirino.