What they were looking for turns out to be the book Mahiro accidentally steals from the library. The robbers utilize both the pen they found earlier and the book to summon a "Great Ape." Nyaruko and Kukko are unable to beat it by themselves so Hasuta has to reveal his true form. Even the three of them together, though, are unable to beat it. The episode comes to an anti-climatic close when Mahiro simply erases the writing in the book to destroy the monster.