After seeing how passionate Marin is about the things she loves, Wakana decides to help her with making outfits. He decides to help her out in making a cosplay for Shizuku Kuroe-tan from the game "Slippery Girls 2." They had planned to reconvene later to get the measurements started, but Marin couldn't wait and ends up coming to Wakana's house over the weekend.

Marin and Wakana start to grow closer as he helps her create her cosplay. Though he's happy about the fact that Marin treats him the same way at school as anywhere else, he also starts to worry about the fact that other people think it's weird that they're hanging out. Despite that, Marin takes Wakana shopping so they can look for materials needed for her cosplay.

Wakana felt relieved just for a moment after they got all of the materials they needed for Marin's cosplay, but then he's shocked to find out that he needs to finish the cosplay in two weeks. On top of that, his grandfather, Kaoru, hurts his back, so Wakana has to run the shop and he also has midterms. Wakana feels overwhelmed and gets depressed, wondering if he'll ever actually become a kashirashi at this point.

Wakana finally completes the Shizuku cosplay. Marin is super excited that she gets to dress as her beloved Shizuku-tan and suggests that the two of them go to a cosplay event the next day. Even though it's her first time at a cosplay event, Marin gets requests for photos left and right. Wakana is overwhelmed with feelings as he watches over Marin, but...

Marin and Wakana have a successful first cosplay event. Because of something Wakana said, Marin's mental and emotional state starts to change a little. Even though she was just spending time at the Gojos' home with Wakana and Kaoru to wash her outfit, she can't seem to calm down. Meanwhile, a certain person comes to Gojo Dolls after seeing the photos Marin posted onto social media of her Shizuku cosplay.

Marin is going to do a group cosplay with her idol, the cosplayer "Juju," whose real name is Sajuna Inui, and they're going to cosplay as Black Lobelia and Black Lily from the magical girl anime "Flower Girl Blaze!!". Wakana heads over to Marin's home so that he can borrow the "Blaze!!" DVDs for research to make the outfits for them.

Juju's photographer and younger sister, Shinju Inui, meets Wakana and Marin for the first time. They're shocked at how opposite her appearance is to Sajuna, but they quickly become closer when they excitedly talk about cameras. Later on, Sajuna suggests that they check out the abandoned hospital that they'll be using for their group cosplay but...

Gojo is able to complete the Black Lobelia and Black Lily cosplays thanks to Marin's help. Both Marin and Sajuna try on their cosplays and they're both excited about how nicely they turned out, and Marin is even more excited about their upcoming group cosplay. When the day finally arrives, Marin and Sajuna get an unexpected visitor.

Wakana and Shinju's secret plan was a success, which added to the success of their first group cosplay photoshoot. As Juju and Shinju look through the photos from the photoshoot, the sisters find out how they both feel. Meanwhile, Marin and Wakana are enjoying their summer vacation. They were preparing Marin's cosplay for a fighting game character named Veronica-tya, but then a problem arises...