A Japanese-American novelist living on a small island in British Columbia, she discovers Nao's diary and becomes deeply engrossed in the young girl's story, which helps her reconnect with her writing.

Nao's 104-year-old great-grandmother and a Buddhist nun who provides spiritual guidance to Nao, teaching her about Zen Buddhism and meditation at her temple in northern Japan.

Nao’s great-uncle and Jiko’s son, who was a kamikaze pilot during World War II and whose philosophical interests are revealed through a secret diary he kept in French.

Nao's father, who struggles with depression and unemployment after moving back to Tokyo, having previously worked as a programmer in California.

A woman who adapts to her family's financial troubles by taking an unusual job as an administrative assistant, later becoming an editor in Tokyo.

Ruth's husband and an environmental artist with a depth of interest in scientific topics, who shares a love of Japanese cinema with Ruth.

A waitress at a French maid café who recruits Nao into escort work, exploiting her under the guise of friendship.

A substitute teacher who participates in bullying Nao at her school in order to fit in with the students.

A popular student at Nao's school who leads her classmates in bullying and abusing Nao.

A geeky classmate of Nao who becomes a reluctant participant in the bullying to avoid being targeted himself.

Nao's popular best friend from Sunnydale, California, who gradually stops responding to Nao's emails after her move to Japan.

A retired anthropologist and neighbor to Ruth and Oliver, interested in Ruth’s discovery of the diary washed ashore.

A marine biologist who assists Ruth by examining the barnacles on the freezer bag containing Nao's diary.

The gossip-prone postmistress in Whaletown, known for her intimate knowledge of the island’s residents through their mail.

A francophone resident who helps Ruth by translating Haruki #1's secret French diary.

A Buddhist nun and Jiko’s assistant who becomes a supportive presence for Nao during her stay at the temple.