I posted this question because I consider to go there, and I'm interested if somebody else would like to attend too.
It's a long travel from Germany to Japan for me, so I think a good reason to attend would be making a presentation:
Application of pgf/TikZ in Science and Technology
Since I'm maintaining TeXample.net with the TikZ Example Gallery, I had contact to many people who used TikZ in their works, mainly in natural sciences but also in electrical engineering and further areas. The presentation is intended to show TikZ' capabilities in this regard, and to talk about experiences with the application of TikZ.
Furthermore, TikZ is the most popular topic on TeX Stack Exchange, so I think it would be a great opportunity to represent our community at the conference in Japan.
My decision to go there may depend on the approval of our TeX.SE community members, if you would symbolically support it, if you like the trip plan and the presentation topic.
I made a similar trip in 2011, if you would like to read about it: The TUG 2011 Experience.