Sumika Murasame's friend, Ushio Kazama, reveals that she has a crush on a second-year girl from the school library, Chizuka Nishikigi. Sumika warns Ushio that Chizuka may have someone else she likes and that Ushio would just get crushed, which makes Ushio unhappy. The next day, Sumika saves Masaki Akemiya from a falling box, though she denies that she is a nice person. Later that day, Chizuka turns against Ushio because the guy she liked had taken an interest in Ushio instead. Sumika, who had waited to apologize to Ushio, then arrives to comfort her and later makes up with her.

Ushio fawns over a cute looking model in a magazine. Meanwhile, Sumika is a bit downhearted that she herself is not what people would consider cute. She becomes a bit surprised when Masaki calls her cute, though it manages to lift her spirits. Sumika tries to confess to Ushio, but is abruptly told she is "not her type" before she has a chance. Just then, Ushio spots the model, who immediately runs off. Sumika chases her on behalf of Ushio only to discover that the model is actually Masaki, who had been crossdressing to get Sumika's attention. She rejects him, but points out that neither of them will give up even after rejection.

Late afternoon at school, Sumika and Ushio catch two girls kissing each other. When the next day's discussion turns to first kisses, Ushio gets the crazy idea of having a practice first kiss. Sumika, feeling a bit dejected that Ushio would rather practice on a model skeleton than her, and decides to take up karate again, having previously quit because she felt it was not cute. The next day, Ushio asks Sumika to meet her after school. Assuming Sumika had someone else in mind, Ushio lets her have her practice first kiss on her while wearing an Ultraman mask. As she does, they are watched by the two girls that Sumika and Ushio had seen kissing each other before.

As Sumika recognizes Tomoe Hachisuka and Miyako Taema as the girls she and Ushio saw kissing the other day, Tomoe whispers in her ear that she saw her with Ushio. Tomoe reveals to Sumika her vision of a girls only club, and Miyako attempts to blackmail her into joining, but Sumika tells her that she and Ushio are not a couple. Both Tomoe and Miyako notice that Sumika has a crush on Ushio, who they later convince into joining them, leaving one more member to find. Sumika decides to use Masaki's cross-dressing skills in order to get reactions from potential girl-liking girls. He goes a bit over-the-top with his confessions and scares everyone off. Sumika decides to try again with his usual wig he wears when cross-dressing as Akemi Yamasaki, but when Ushio spots him, he is enrolled into the club and 'Akemi' is made into a transfer student. However, the club application is rejected.

Tomoe and Miyako come to Sumika's house for a study session, although they are really thinking up plans for their girl's club. Sumika has trouble juggling both them and her in-house maid who embarrasses her. The next day they decide to take their 'studying' over to Ushio's house, where Sumika notices she and Ushio both have the same photo of each other taken on the first day of school displayed in their rooms. Preparations for dinner soon turns into a battle between Sumika and Miyako, which ends with explosive results. After another failed attempt at working together to cook, Ushio's brother, Norio, arrives with some takoyaki and are later joined by their friend Kiyori Torioi. After leaving, Tomoe and Miyako thank Sumika for helping them get friends. When Sumika gets home, she prints out a photo of the five of them together.

Ushio is still having trouble facing Chizuka following the incident between them, even though she allegedly wants to apologize to her. Noticing Chizuka's clumsy traits, Tomoe and Miyako decide to train Sumika into becoming a clumsy girl that Ushio would fall for, with poor results. Later, Ushio comes over to Sumika's house instead of going to meet with Chizuka. Sumika notices Ushio is lying about not having feelings for Chizuka anymore. Later that night, Ushio offers to wash Sumika's back, but Sumika just ends up fainting from embarrassment. Ushio berates herself for selfishly liking and then disliking Chizuka, but Sumika tells her it is not her fault. The next morning, Ushio goes to Chizuka to apologize and confess, much to Sumika's dismay.

Masaki's younger sister Manaka sneaks into school to confront Sumika over why she rejected him. Using some pity tactics, Manaka manages to get Sumika to agree to go on a date with Masaki. Come Sunday, Masaki meets up with Sumika while cross-dressing, and Manaka follows them, using a plan to get them together. Meanwhile, Ushio gets a little worried when she cannot get into contact with Sumika. Manaka recommends they go see a romance film, but they end up watching a horror instead. Next, Sumika and Masaki have lunch, though Manaka is unable to sneak love potion into Sumika's food due to her unconvincing waitress disguise. While clothes shopping, Sumika cannot handle the fact that Masaki acts more cute and girly than herself, and she runs off only to be ambushed by a trio of creepy otaku Manaka had recruited to make Masaki look like a hero. Masaki leads them away from Sumika, but soon finds himself in trouble when they will not leave him alone even after he reveals he is a guy. At the end of the day, Masaki simply tells Manaka not to do something like that again, while Sumika checks her phone to find six voice messages from Ushio.

Some classmates ask about whether Tomoe and Miyako are actually dating. When another classmate, Azusa Aoi, complains about such scandalous talk, she gets kissed by Tomoe and runs off in embarrassment. Sumika later catches up to Azusa and learns she is a fan of Masaka Orino, who unknown to her is actually Norio's pen name. Learning Sumika has heard of 'her' works, Azusa feels relieved and becomes friends with her. Just then, they fall down some stairs, only to be spotted by Ushio in a compromising position. Sumika catches up to her, and to both of their surprise, Ushio starts crying. Noticing the awkwardness between them, Tomoe arranges for Sumika and Ushio to have a private talk. Ushio assumes her tears were from seeing Sumika acting like a violent man, but knows she wouldn't really do something like that. Azusa appears out of the blue, bring with her some dōjinshi of Orino's work, putting pressure on Ushio to keep Norio's identity a secret. As Ushio leaves, Sumika notices her blushing as she goes.

Azusa gets psyched to prepare a doujin for an upcoming yuri convention, assuming Sumika would help her with it. Ushio decides to distance herself from Azusa so that Norio's secret identity won't be found out. Tomoe plans a trip to the beach for her 'club', tempting Sumika with the thought of Ushio in a swimsuit. Thinking about Sumika, Azusa is inspired to work on an original story as opposed to a doujin, and spends many nights working on it with the hopes of showing Sumika the final result. However, she becomes very depressed when Sumika can't remember offering to help, and runs home to cry. Having noticed her, Tomoe brings Sumika over to Azusa's house so she can see the work Azusa had done and apologize.

Sumika ends up working with Azusa to finish her doujin for the yuri convention, hoping to finish in time to join Ushio and the others on their trip to the beach. However, unbeknownst to her, their trip is cut short due to Tomoe wrecking their rented car. As they approach the end of a seemingly endless amount of photocopying, Azusa notices a spelling error. Sumika can't stand leaving it there, so she makes further copies, having to visit several stores to get a working copier. However, when she finally gets back, she trips up and spreads all the copies everywhere, causing Azusa's mother to slip and spill drinks all over them. Noticing how distraught Azusa becomes as a result, Sumika decides to forgo joining the gang and helps her salvage the remaining copies for the convention. To Sumika's surprise, Ushio shows up at the convention to see her and buy a copy of their doujin.

To make up for missing the beach, Azusa's parents gets everyone tickets to the pool. Ushio decides to keep her distance from Azusa so Norio's secret won't be found out, which annoys Sumika since she's the only one Azusa knows well. Conveniently, Kiyori separates everyone into two groups based on their breast size, putting Sumika with Ushio and Tomoe. Ushio and Tomoe get hit on by some guys, but Sumika scares them off when they show no interest in her figure. Sumika then gets competitive with Tomoe over her swimming ability, but inevitable loses. After recovering on Ushio's lap, she teaches her how to swim. As they do, they are spotted by Azusa, who realises Sumika has feelings for Ushio and wonders if she was just in the way. She does find a little comfort after talking with Tomoe and decides to write a story based on the two.

On a rainy day, the gang discover a hidden note in a book referring to a certain thing, so they decide to search for it. After some investigation they find a key to a locker, but are reluctant to go to the boy's locker room, so Sumika gets Masaki to go for them. The locker contains another note mentioning a German person. With Azusa's help, they make the connection to the pictures of German musicians in the music room. This leads them to the creek (which in German is 'Bach'), eventually finding it to be a prank, but having fun all the while.

Sumika goes with her family on a trip to visit graves and an obon festival, promising to call Ushio when she gets there. However, the house they were meant to stay at got damaged in a fire, so they are relocated to a temple on a mountain which, much to Sumika's chagrin, is out of her cell phone's range, meaning she can't contact Ushio. The next day, Sumika is put in charge of looking after some children. Whilst visiting the river, one of the children, Teru, falls off a tree into the river, and Sumika goes to save him, getting her cell phone wet in the process. Meanwhile, Ushio gets concerned that she hasn't heard from Sumika, wondering if she got caught up in an accident or something. Teru apologises to Sumika for causing her trouble and gets grounded. When Sumika's phone starts working again and Ushio calls it, Teru rushes it over to Sumika who is attending a festival and the two finally get to talk to each other.