Mystery of Class 1-3 (クラス1-3の謎)

During the spring of 1999, high school student Clarissa is reportedly missing after taking her way home via subway train at Miyagi Station.

Members of her family had notified the police that their beloved one did indeed suffer from bipolar depression and had been given approx. 50 million yen as part of her share of her deceased parents' will.

However on April 1 of the same year,
Clarissa's body is found chained to the body section of a Tokyo City bullet train.

News reporters reported that over 500 passengers had died on board the train as Clarissa's body was brutally stabbed, wounded, and decapitated due to a rather severe collision.

500 of Class 1-3 of Japanese International League High.
Only 1 survived.
The man is convicted of planning the accident and Clarissa's kidnapping.

However Class 1-3 is not at all what it appears to be...
As both Clarissa and her admirer were both on the same train...

The man, Hiroki was not seen in any of the official lists of students who were on it.