As Yūta becomes curious about why Shinka would want to join the hobby group, she asks to go to his home on Sunday. Yūta attempts to get Rikka out of the way on that day by sending her and Sanae off on a wild goose chase. As Shinka arrives at Yūta’s home, she frantically ravashes his room searching for a book of Sanae’s that Yūta had in his room. Yūta soon discovers this ‘Mabinogion’ is in fact Shinka’s journal from her chūnibyō phase, when she called herself Mori Summer, which she wanted to destroy before anyone found out about her embarrassing past. As she burns the book, revealing her true nature that she only joined the club to get rid of it, she is shocked to learn Sanae has multiple copies. With Sanae unwilling to listen to her as she doesn’t believe her to be the true Mori Summer, Yuta suggests she appeal to her delusions, but ultimately cracks under the pressure. Shinka reluctantly decides to stay in the group until she can finally destroy all of the evidence.