Summer vacation is coming to a close. Wakana received an SOS from Marin, who hadn't finished her homework, so he ended up helping her study at her house. They later realize that Marin had forgotten some math drills at school, so they go to get them. While alone at the school, Marin and Wakana make plans to go to a summer festival together. And when that day finally arrived...

Liz is a succubus who appears in one of Marin's favorite slice of life series, "SuccIDK." Marin had some interest in cosplaying Liz-kyun but didn't think she could pull it off until Wakana gave her a little push. With the cosplay ready, they head to a studio for a photoshoot, but the studio happened to be a rather unexpected location.

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...

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.

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...

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.

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.

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...