A: The world where magicians, sennin and tengu reside is the "Minor Heaven" of the spirit world. The "backside" of the spirit world is a strange place.
In the Spirit World, there are not only differences on the vertical level but also on the horizontal plane. To be more precise, there is the Major Heaven where spirits who have achieved spiritual growth and evolved in an orthodox direction reside, as well as the Minor Heaven inhabited by magicians, sennin and tengu.*
A good example of the Minor Heaven is the world of Harry Potter. Several movies have been made in this series, so you may have watched them or read the books. While the world of magic is fun to read about, when it appears in movies, there are lots of scenes that are quite eerie.
But this is not to say that the realm is entirely a part of Hell. While it is indeed one of the realms of the other world, it is different from the crystal-clear world of spirits that I usually teach about.
This is a place where many eerie, uncanny and fantastic events occur; it is a kind of magical world. The appearances and words of the high spirits described in Happy Science are of the sort that we would expect; how great figures on earth would appear and what they would say if they had continued to evolve in the next world.
On the other hand, Harry Potter describes a mysterious and weird world where the characters cast spells on one another. In Japan, we have the movies by Hayao Miyazaki, which deal with similar kinds of realms. His Spirited Away  and Princess Mononoke  depict many scenes from the Magician, Sennin and Tengu Realms.
While the Japanese Spirit World and the Scottish Spirit World are different, the worlds of Miyazaki and Harry Potter have a very similar atmosphere. These are what are referred to as the Minor Heaven.
In Japan, there was a man named Onisaburo Deguchi, who founded the Omoto religion and was active during the first half of the 20th century. He originally came from the Minor Heaven. He published a book entitled, Reikai Monogatari [Tales of the Spirit World] in which he described his travels through various realms in the Spirit World. While this is an old book and difficult to read, it contains stories of numerous fantastic worlds that are just like those depicted in Harry Potter or Miyazaki’s films.
There are numerous stories of foxes or raccoon dogs that bewitch each other, worlds where snakes suddenly appear and worlds in constant change where creatures transform themselves into a variety of shapes.
Happy Science has published two volumes of spiritual messages from Onisaburo Deguchi [Okawa Ryuho Reigen Zenshu, 46, 49, (A Collection of Spiritual Messages by Ryuho Okawa, Vols. 46 and 49) (Tokyo: Happy Science, 2008 and 2009)] and, for the most part, these deal with the Minor Heaven. These are about the kind of world where the inhabitants fight with psychic powers using magic, trying to transform their opponents into different forms. There is actually a world that is based around magic.
* Sennin are fond of psychic powers, magic and spiritual phenomena and are always involved with these matters. Tengu like to boast of their powers or wisdom.
Spiritual world 101