"It's about the otherworld in Swallowstone Naturalis Historia that was mentioned on the show.""Wanting to turn that coincidence into certainty, I sent you this letter.""I myself am someone researching the occult. It was a total coincidence that I listened to this show.""It was all in a dream, but the world was all real.""A rental bookshop flourishing with not even any e-books, and no air-conditioning anywhere.""A religious war, the wrath of youkai and gods...""Villagers walled in by nature, the children from the temple school""A certain shrine with a big torii""A bamboo grove that leads people astray, an upside-down Japanese castle""It seems extremely similar to a certain otherworld I'm familiar with."