I'd see if you can find any of the collected essays or interviews of Tezuka. I've read about some of the essays/interviews and it's really interesting to see what his view is on different subjects.
As for his manga work, I'd say to look at the lesser known works such as Mako, Rumi, and Chii, Unico, Bomba, Tezuka's Ancestor Dr. Ryoan (also known as A Tree in the Sun), Duke Goblin, Grand Doll, Don Dracula, Rally Up, Mankind!, The Devil Garon, and Yakeppachi's Maria.
There's also the unusually dark novella, The Deadly Mushroom, which stars Hyoutantsugi.
Hope you enjoy your time in Japan, strobe_z!