Focuses on one series in his work—trees.
As a result, I found it a nice touch that "Japan Diaries" is essentially a transcribed daily journal of two month-and-a-half to two-month trips taken to Japan across a ten-year stretch (1987 and 1997). Without being condescending or offering "the key" to understanding Japan (as far too many Japan travelogues try to do), this book offers a very readable, very day-to-day view of visiting and living in Japan - especially when you come to the country with minimal first-hand experience with Japan itself.
However, if it doesn't offer an arrogant viewpoint it's also not the most insightful book on Japan, either. Not that the author doesn't work hard to give a good background on the various things she talks about - and to be very clear to lay out her own biases in everything she talks about - but she also occasionally fails to understand what's going on around her, such as the background reasons for why foreigners find it so hard to rent an apartment in Japan.
On the whole, though, this is definitely light, interesting reading, perfect for a couple of days on the beach or a long airplane flight. Sherman does as good a job as anyone else I've read of making you feel like you were taking the trip with her. And when it comes down to it, isn't that what travel writing's really all about anyway?