Touhou Double Focus

At a certain rental bookstore in Gensokyo... Like any other day, Kosuzu Motoori tended to the store until one book caught her eye. Although she was quite knowledgeable about magical books, she had never seen anything like it. After making sure no one was around, she stroked the cover with her finger. "Book...King? I guess I'll try reading it." She pulled up a chair, took a seat, and got ready to open the book. It was unbeknownst to her, however, that this would mark the beginning of an incident that would involve all of Gensokyo.