This game is a Spectator Entry for an OCT called DreamCatcher. The plotline is that people have been falling into a coma and waking up in a magical place called DreamCatcher HQ. There is only one way out and that's to compete in a tournament for a failsafe.
Hazel isn't interested in saving herself or competing with anyone. She ended up in a hospital ward under near constant supervision after becoming a risk to herself. The hospital she is in ends up being attacked by a monster named "Head Heads".