Gensou Rougoku no Kaleidoscope

I was trapped in an eerie room I had never seen.

Before I knew it, everyone had an iron collar on their neck. A chain was attached to the collar, leading to chairs in the four corners of the room.

When, how, and by whom were the four girls who were close friends taken here?

An ominous voice echoed throughout the room.

"I have two fateful preparations for you.

One: everyone in the room is destined to die. The other is that only three girls are destined to be saved. This is a test of fate for you four girls.

When the time limit comes...everyone in this room will die."