Doukoku Soshite...

On the school bus, mid-conversation with a classmate named Riyo, a car comes out of nowhere and the bus is struck. The hero wakes up to find himself, most of his classmates, and a handful of strangers locked inside a room in an unfamiliar mansion. Then one of them is murdered. The killer is somewhere in the mansion too, and the evidence — a bloodstained memo, a photograph — raises more questions than it answers. Survive. Solve it.