Nao lives in Tokyo. She is sixteen, and has decided to write a diary before she kills herself. She has plenty of material - school bullies, depressed parents - but she particularly wants to chronicle the life of her great-grandmother, Jiko, a Buddhist nun. Eventually, Nao thinks, her diary will find its reader.

Ruth lives with her husband on the Pacific coast of Canada. A few months after the 2010 tsunami, she finds a Hello Kitty lunchbox washed up on the shore. It contains a diary.

This is the simple story of a girl, her great grandmother and the novelist who becomes enthralled with their tale. And it is much much more.