Every so often, somebody is born a little different, with a Daemon inside their mind. Daemons are additional consciousnesses that manifest within a person's brain and can interact with them mentally. Most consider their Daemon's to be like imaginary friends that took on life of their own, or some kind of split personality disorder.
Daemon-holders rarely tell others about their partners, but on New Years Eve, 2020, they wouldn't be hidden anymore. A magical apocalypse struck Earth, bringing all Daemons out of their hosts' minds and into reality. In addition, all Daemon-holders gained inherent magical powers, with apparently no limit. The world was thrown into chaos as thousands of new beings, most never seen before, began to populate the Earth and those with Magic started to learn how to use it. And over time, the inherent magical potential of all humans will begin to unlock.
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So this is sort of SMT themed with all the characters having personal partner creatures/monsters/what have you and facing a major struggle on the planet after a significant apocalypse. In addition, a number of magical phenomena begin to spread over the earth, threatening human life even further. It would be the protagonists' job to try to bring balance, or chaos, or strict order, depending on their proclivities.