Mayumi, who struggles with social interactions and cannot find value in herself... The cause of this lies with her high school best friend, Kiriko. While manipulating things to keep other friends away, Kiriko ended up marrying and getting pregnant with Mayumi's fiancé's child (or so it was supposed to be). Despite her seemingly smooth life, she unexpectedly appears at "Umineko-so." While trembling in fear of the source of her trauma, Mayumi begins to realize her feelings for Rin more and more... This is the final volume that creates a new form of family.