This was a contemporary Japanese film. It begins with two siblings, boy and younger age girl, going off to school on a bus, waving goodbye to the mother. That is the last time they see her. The bus gets hijacked. The children survive and are found living alone in their home ( I cannot recall why the parents are not there) The bus driver also survived and hunts them down. He finds them living in squalor. He moves in, looks after them and sometime after takes them on a long bus ride through a countryside, a remote area in Japan,to finally arrive at the seaside. Along the way the boy has given himself up to a police station for something he did. My memory is dim in parts but the movie has haunted me for  years since I saw it. Does anyone recognize this?