I would encourage you to take photos of the trees with permission and spend your time soaking up what makes the bonsai in Japan so great. Even photography at a bonsai garden without a backdrop is a challenge. You can call Fujikawa Kouka-en (kakejiku listed the contact info above) once in Japan via your hotel concierge. It's where I study, and easy to get to from Umeda Station. It's best to keep your visit down to a reasonable time, and to avoid directly preventing work to be accomplished : ). It's customary to buy something, even something small when visiting a bonsai garden, and also to bring some small gift to show appreciation. Average Japanese folks can't just show up to high end bonsai gardens to look around, but international visitors are not constrained by those cultural norms.
Importing from Japan legally on your own is not really worth it. It's worth the mark-up to buy from those who already have trees in-country if you have your heart set on Japanese imports. Your trees could be torched at the port for just about anything. I'm not going to go into the entire process, which I pursued, as it is infinitely frustrating and I'll get worked up. It will be far easier to get permits to transport trees from the USA back across (William N. Valavanis), or you could buy trees from David Easterbrook in Montreal. I know a few people in Toronto who sell their bonsai, so please PM me if you'd like to make contact.
You can however, buy just about anything small and alive from China (where many of our worst pathogens for plants have been imported from) with their fake phytosanitary process and more lax trade deal.
Makes absolutely no sense.
I ordered 100 fruit trees via Alibaba just to see what would happen, and two weeks later, I had 100 fruit trees from China. Wrong species and they were all grafted high. But, I was able to get non-quarantined trees that can carry a bunch of different diseases and pests affecting other genus. You cannot legally import large trees from China without apparently bribing the correct people; also cost prohibitive and could potentially unleash the next Sudden Oak Death, Boxwood Decline, Emerald Ash Borer, Camphor Shot Borer, etc.
@junmilo, I'm writing this for all who visit Japan, and hope this helps any others who plan to visit in hopes of legally buying bonsai in Japan.