Your comments about the image of Toyama being off sent me scurrying around the web, jc.
Whoops! Sorry about that. I meant to include relevant URLs, since I caught the motherlode:
http://www.toyamamitsuru.jp/syashin/index.htmlOf course, the captions are in Japanese, which doesn't help, but the Internet comes to the rescue with free tools.
http://www.appliedlanguage.com/web_translation.shtmlBut the upshot is that we can see him at 25, 45, 60, 70, and 80.
Given the correlation of likenesses with the (then) contemporary Toyama (and with Tojo as you point out), it could be that back then there was no available reference of him as a young man. Comments?
I suppose it's possible, but he doesn't seem to have been reclusive prior. However, I should amend my original statement in that the splash looks like the eighty-year-old Toyama, which is one of the pictures I neglected to look at. He aged a lot more in those ten years (seventy to eighty) than I would've ever expected.
As to the availability of material, I don't even think I could hazard a guess. He's not listed in the 1911 Encyclopedia Brittanica (available for download at the Internet Archive), unfortunately. I'm also stymied in finding the obituary listed in Wikipedia, since the New York Times charges four bucks for the honor of reading a sixty-four-year-old page (since there are brief comments on two pages, that's eight bucks for about a thousand words and maybe a picture). Google Books is also a bust, though it turns up some of Toyama's own words from 1922 regarding the Washington Conference. Here's the relevant page.
http://books.google.com/books?id=QV6ena5_h4oC&pg=PA149&sig=ACfU3U3UsD2-bjdnmxYi8ZQpzWvofOGWegHowever, even though it's not illustrated (though I assume that it was in print), Time Magazine was more helpful with background:
http://www.time.com/time/magazine/article/0,9171,765147-1,00.htmlSince that was published in 1941, I'm going to guess that it's the main source of the author's information. If it was published with pictures, then those images were almost certainly the core of the artist's research, as well. And now that I think about it, the Times obituary is probably irrelevant--if the book has a cover date anywhere in 1944, then they didn't get any information from any October 1944 article.
Incidentally, it's interesting to compare this depiction of Toyama with his lightly fictionalized (and anonymous) counterpart in All-Star Comics #12.
ps. there is a [Preview] button in the Post Reply window, but all I ever get is a "Fetching preview..." line in the Preview Post window. Is there something I don't know about?
I know it used to do something, because I hit it accidentally a few times instead of posting, early on. Looks dead now, though.