Chronicles of a Hundred Ghosts

Long ago, demons ran rampant in the mortal world, leaving people in misery. Seven ancestors used the gemstones born alongside them to seal the demons behind the Gates of Hell. Their descendants spread across the world. Every child is born alongside a gemstone, which chooses whether to recognize its bearer, judging whether they have the talent and perseverance to inherit it. Once they inherit a gemstone, they become a hero. The gemstone assigns them a role based on their strengths and personality, and grants them a weapon that only they can wield, so they can eliminate the demons left behind after the Gates of Hell were closed. But more than a thousand years ago, or so the story goes, someone broke the seal on the Gates of Hell, and ever since, the gates have opened from time to time.

But is that really what happened?