I thought if we stayed over, we would get along better? (お泊まりしたら仲良くなれると思った？,Otomari shitara Nakayoku nareru to Omotta??) is the ninth episode of the Netoge no Yome wa Onnanoko Janai to Omotta? series. It aired June 2, 2016.
To persuade Ako to get cracking on her summer vacation homework, the girls have a study session sleepover at Kyoh's gigantic house. However, without Hideki around to keep Ako under control, things soon get out of hand.
It's an all-girls slumber party at Kyo's extravagant mansion as they gather to finish their summer break homework, especially Ako who hasn't made any progress with it. Cut off from contact with Hideki as well, the other girls take this as an opportunity for Ako to socialize without having him there, much to her chagrin. As the girls are led by a maid into Kyo's room, Ako struggles to stay focused and gets up for a bathroom trip. Distrusted by the others into believing she'll run away, Nanako walks with her, and the pair soon become caught up exploring the mansion due to Ako's curiosity. Stumbling upon a study with a hidden room behind the bookshelf, they become chased by the maid after discovering a secret book chronicling Kyo's "growth" and the lost pair calls out to the others from the courtyard. While they decide to carry out the remainder of their work from there, Ako's minimal progress draws the attention of a frustrated Akane. After going through dinner and bath time, Nanako asks Ako about Hideki's preferences in girls, to which not even she doesn't know. With cellphone in hand, Ako prepares to contact him as the others realize the troubling situation, where her video chat will leave the girls in full view of their naked bodies. While Ako leads the girls on a chase, Nanako manages to calm the dilemma as Ako throws her the cellphone only for her to turn it off. As the girls get settled in a single bed, Nanako also questions Ako about the views of her wife mentality, where she gives a scenario in how husbands and wives in the game and in real life have certain bonuses. Perceiving Ako as unfaithful, the girls quickly log into Legendary Age to confront Rusian about his views on Ako's mentality.