Character introduction

A high school girl student called Daisuke. Her father died a long time ago. When Daisuke transfers to another school, she needs to take a train to the school. One day, she is taking a train to school. She knows a boy who is called Kai. When Kai was 5 years old, his mother died. When Kai's father married his stepmother, his father abandoned Kai. Every day, Kai always stays on the train. A day after a day, Daisuke and Kai became friends. But one day, Kai, it's time to leave the world...