First, like many haiku, the meaning of Ozeki's title can shift as you think about it. It can mean "a tale or the present; until some other arrangement is made." Or it can mean "a tale for the time creature; for the living thing." Both apply.
Ozeki, a novelist who has published two other books and lives part time in British Columbia, writes half the novel's chapters in the third person from the point of view of Ruth, a novelist who lives on a small Canadian island north of Vancouver with her husband Oliver. In her acknowledgements, Ozeki thanks her husband Oliver.
Half the novel's chapters are written in the first person by Nao Yasutani, a 16-year-old Japanese girl living in Tokyo after growing up mostly in Sunnyvale, CA, where her father was a computer programmer. Nao is writing in English, but her diary contains Japanese words that Ozeki helpfully footnotes.
Back in Tokyo after the dot-com bust, Nao's father is suicidal and Nao finds refuge for a summer at a temple in the north where her 104-year-old great-grandmother, Jiko, is a Zen Buddhist nun. Jiko's son, Haruki, was conscripted into the Japanese military in 1943 and trained as a suicide plane pilot.
At the beginning of the novel, Ruth discovers a Hello Kitty lunch box in the beach wrack along the shore of her island. It contains Nao's diary and her great uncle's letters (written in French so the NCOs training the conscripts cannot read them). Ruth has been trying to write a memoir for ten years, and becomes caught up in Nao's diary, which involves bullying at school, her father's suicide attempts, her summer at her great-grandmother's temple, and more. Ruth also reads Haruki's secret French diary.
I hope these shards of information I've just sketched hint the complexity and richness of A Tale for the Time Being. Given my own experience with Japan, other things I've read, and Ozeki's footnotes, she produced a sense throughout the novel that this is what's it's like to live on a small Canadian island in the Northwest, to be a Japanese schoolgirl who has been contaminated by her life in America, to be a peace-loving 19-year-old conscripted by a monstrous war machine, to be a 46-year-old Japanese father unable to find a job, to be an elderly Zen nun. This is what it's like. These incidents are entirely possible. These are the tragedies of history . . . and of human character.
It includes the problem of time: What you are reading now came into existence in the past. I myself may no longer exist when you read these words. And if I were writing to ask for help, as Nao does even as she has no idea who might read her words, what would you be able to do? Particularly if you are on one side of the Pacific and I am on the other? If you are a novelist, you would make a story.
All I can recommend is that you find and immerse yourself in Ozeki's novel for a deeply moving and thought-provoking experience.