Rei:Rise of Fate: Shattered Holy Aldeerm Stone-Gem Death Royal

In a world full of magic and adventure... wait, what was that? In a world where magic is scarce... I'm try to talk here. In a world that is average, where the people aren't trying to kill you... unless you go to a school. Unfortunately for the protagonist, Emerald, who goes to school cause she's a highschooler. Blah blah blah plot, character development, magical gem. There we go found it! Emerald was one of many few people who enter a death game where a majority of the candidates are kids in their early teens, kinda like Harry Potter but less standing and more stabbing. Emerald summons a legendary spirit, or a really well known persons. Except hers who's so obscure you'll be wondering if he actual exists. With bull powers you'll be wondering, why the heck doesn't he do this more often? Why does it sound like the writer is crazy? What time is it? Why is this Synopsis so long? Because I could sum it up in a sentence. This story is about a girl dragged into a child murder game who summons an overpowered spirit who spends most of the playing around. See, what kinda Synopsis is this? Anyways after their first night together a shadowy figure stands above them watching from the shadows. Who is this? What is their goal? What are they up to? Who are they working for? We'll know eventually... maybe...