Tokyo Vice: An American Reporter on the Police Beat in Japan, by Jake Adelstein. Mr. Adelstein is a frequent contributor at the Japan Subculture Research Center.
The Japanese have words for sadness that are so subtle and complicated that the English translations don't do them justice.
Setsunai is usually translated as "sad," but it is better described as a feeling of sadness and loneliness so powerful that it feels as if your chest is constricted, as if you can't breathe; a sadness that is physical and tangible. There is another word, too - yarusenai, which is grief or loneliness so strong that you can't get rid of it, you can't clear it away.
There are some things like that. You get older and you forget about them, but every time you remember, you feel that yarusenai. It never goes away; it just gets tucked away and forgotten for a while.
There is a beautiful children's song, written by the artist Takehisa Yumeji, called "The Evening Primrose." The evening primrose is a yellow, sometimes white flower that blooms only at night, then tinges with red in the morning and withers. The song is almost impossible to translate because it says more in what it does not say than in what it does. Any translation would be an interpretation. But here's mine.
You live and wait and wait and wait
But the other may never come
Like waiting on the evening primrose
This feeling of sadness without end
This evening, it does not seem
That even the moon will come out.
It's that one email you never replied to and will never open. It's the bad advice you gave and the phone call you should have made and everything that came out of it. It's thinking about the friends that you suspect you might have been able to save.