I tried as well everything to get Tanaka's autograph but unfortunately without luck.
My friend Makoto in Japan helped me and read his biography and wrote him a very nice letter in Japanese
Unfortunately even with this afford only following reply from the secretary of Mr.Tanaka.
In the letter, he writes as follow,
"not signing" is one of Mr.Tanaka's policies (of courese he signs forcontarcts etc.).
All things I sent except letter were returened to me by SHIMADZU (company that Mr.Tanaka works) envelope.
Shortly, SHIMADZU paid postage for sending back.
I think the company is honest but Tanaka can be considered as the rarest living Nobel Prize laureate autograph.
He is one of 7 autographs which are missing in the most complete personal Nobel Prize autograph collections.