One morning, on her way to school, carefree, daydreaming Yua Serufu wrecks her bike and an upperclassman comes to her rescue—a chance encounter which sends her down a path to answer the question, "What does 'DIY' mean?"

When Purin sees Jobko through Serufu’s window, she heads over and gets introduced to the girl genius. The two end up hitting it off. Then, the next morning, Purin wakes to find Jobko in her room saying that she’ll be living there—effective immediately.

Midterms are over. The parts for the secret hideout have been ordered. Kurei has announced that they’ll start building on Monday. Serufu asks everyone to come to her house on Sunday, before building starts, so that she can show them something.