Wakana Gojo is a high school student who dreams of becoming a kashirashi for hina dolls one day. Because his life is all about making hina dolls, he has a hard time fitting into his class because his interests are so different than anyone else’s. His classmate, Marin Kitagawa, is always at the center of attention and from another world. One day, they both end up on classroom cleaning duty and…

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.

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...

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.

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...