In the 1980s the Japanese novelist Aya Nishitani was working for an electronics manufacturer. As a child he had an interest in astrology and had researched western black magic; as an adult he had developed astrology software for the PC market. In his own (translated) words, "the use of black magic is limited by the position of the planets, but if we use similar circumstances on the PC, we can conduct countless simulations any time we want."
In the midst of a growing number of home PC users and the rise of hobbyist computer programmers there was a certain apprehension and unease about the new capabilities of computer technology. This was also the decade of Cyberpunk; novelists like William Gibson and manga aritsts like Katsuhiro Otomo helped solidify the genre in the US and Japan respectively, with grim portents of a dystopian future where technology has only served to widen social and economic schisms and where citizens are under constant surveillance. Thank goodness that never came true! : )
It was in this historical context of technological advancement, political and social unease, and a personal interest in the occult, that Nishitani wrote his first serialised novel, Digital Devil Story: Megami Tensei.
The novel is about Akemi Nakajima, a high school student and computer prodigy who has an interest in black magic and gets bullied for being intelligent and attractive. I promise he is not a stand-in for the author. In a flash of rage-fuelled inspiration he suddenly realises that the kinds of rituals that were supposedly once used to summon demons could be automated by a computer program, and develops such a program in order to enact revenge on his schoolmates. Unfortunately he summons the Norse god Loki, who turns out to be an extremely powerful demon and very quickly overpowers Nakajima and attempts to take over the world.
Nakajima joins forces with a new student named Yumiko Shirasagi, with whom Nakajima seems to share a strange bond and shared memories of a past life. It later turns out that Shirasagi is actually the reincarnation of Izanami, a Shinto goddess of creation and death - this is where the book gets its subtitle, Megami Tensei ("Goddess Reincarnation.") Nakajima is himself a reincarnation of Izanagi, Izanami's former husband, which explains their connection.
According to Shinto mythology Izanami died during the birth of their child and Izanagi traveled to the underworld to bring her back. Unfortunately Izanami had already tasted the food of the underworld and had become one with it, and when Izanagi found her he saw that her skin was rotting and covered in maggots; he could not contain his fear and ran from his wife and pushed a boulder in front of the doorway to the underworld, separating the realms of the dead and the living and abandoning Izanami. In the same way that Nakajima has to atone for the deaths he caused in summoning a demon during his IT class, he must also symbolically atone for Izanagi's act of cowardice and save the reincarnation of his former wife. Also he can summon Cerberus and he is just a big ol dog with only one head. He's a good boy and I like him a lot.
If that plot sounds dense then you should also know that the novel is like, 60 pages long. It obviously relies a lot on assumed cultural knowledge - the story of Izanagi and Izanami is to Japan what the story of Orpheus and Eurydice is to us - but it still covers a LOT of ground in a very short amount of time. It's also kind of misanthropic, very misogynistic and has a lot of really gross and violent imagery that makes it hard to recommend. If you are a fan of weird and problematic sci-fi pulp novels then there is an English translation available to read online.
There was also an OVA (direct-to-video animated film) that adapted the book, but that is also hard to recommend because it is also gross and disturbing - if you know anything about adult-oriented Japanese animation from the 1980s you can probably imagine - and also it's only 45 minutes long, which means it has nowhere near enough time to tell any kind of narrative and it barely makes sense without having read the book first.
So I guess that leads me to the reason I sought this book and OVA out in the first place: the book was also adapted into a video game called Megami Tensei in 1987. It's a role playing game where you, as Nakajima and Shirasagi, attempt to rescue Izanami and escape a massive labyrinth controlled by Lucifer and his minions, Loki and Seth. It is so weird and creepy but it also removes all of the stuff that made the source material difficult to enjoy. The music is awesome and the core game mechanic is that you either attack and kill demons, or attempt to negotiate with them and add them to your party. It's basically like a halloween version of Pokemon, except 8 years earlier, and all of the Pokemon are mythical creatures and religious figures that you can talk to and bribe. You can use the Archangel Michael and a Basilisk to beat up a werewolf. It's awesome.
Megami Tensei's developers soon decided to reboot the series away from its source material so that they could tell whatever story they wanted; the result was Shin Megami Tensei, one of the longest running and most prolific game series to come out of Japan. It's probably my favourite series, mostly because of just how much it has going on; it's taken all the dangling threads left behind by Nishitani, weaved its own into the fabric and made a spiderweb in the shape of the Kabbalah Tree of Life. It even has its own spinoffs, like Devil Survivor, which focuses more on strategical combat, and Persona, which combines the core gameplay of SMT with the everyday social life of a high school student, the key concepts of Jungian psychology and the symbolism of the Tarot's major arcana - it is somehow more popular than its parent series, even though it's even harder to explain to people. I love everything about SMT and it's getting a fifth mainline title soon and I can't wait to play it.
I feel like I've sold Aya Nishitani a little short in all this; despite how I may feel about the tone and content of some of his writing, he touches on some really interesting and powerful ideas. At one point in Digital Devil Story, Loki draws a comparison between Nakajima's revolutionary demon-summoning technology to nuclear arms, and in a way Nakajima's attempts to wield a weapon that can easily overpower him reflects that. In the first Shin Megami Tensei game, the world is obliterated in a tactical nuke that is intended to quell a demon invasion but wipes most of humanity off the face of the earth in the process. In 1980s Japan, the fear of the recent future and memories of the recent past must have been in constant conflict. .