I'll mostly be in Tokoyo area but could make a trip for something.
October
Yusui-ten, Tokyo. A Satsuki tree exhibit.
Kinashi Bonsai Festival, Takamatsu. Held late October.
November
Shuga-ten, Tokyo. Medium sized Shohin exhibition organized in early November.
Annual Bonsai Exhibition, Takamatsu. Held mid/late November.
Taikan-ten, Kyoto. A Large Bonsai exhibition held in late November.
Kyushu Miyabi-Ten, Kumamoto. A small shohin exhibition held late November.
Throughout the year several Bonsai, Shohin and Suiseki Exhibitions are held in Japan. By far the most important exhibition is the Kokufu-Ten, where the highest quality Bonsai trees of Japan are
www.bonsaiempire.com
Going to Taikan-ten would be at the top of my list that time of year.