Well, it turns out there were two teams that weren't in my actual predictions:
Tohoku Memorial Bid - Yamagata Chuo (2nd appearance, 1st in 3 years) - C
Yamagata Chuo is still a curious choice to me. The exclusion of Sakata Minami made some sense, but I really did believe that Aomori Yamada would be invited.
But, with Yamagata Chuo receiving the Tohoku Memorial Bid, it's possible that the committee had different criteria for making this particular selection.
I have little on Yamagata Chuo, though actually a bit more than I first thought. They did have a in-prefecture quality win against Yonezawa Chuo in the semi-finals before losing to Sakata Minami 3-2 in the final.
Their ace is righty Ishikawa Naoya (石川直也), while their main reliever is southpaw Takahashi Kazuki (高橋和希) - yes, I managed to find videos. Their captain is Matsuzawa Shouta (松沢昇太), and their kantoku, Shouji Hideyuki (庄司秀幸) is a young 36 years old.
But that's about all I could find. They've had rather bad 1st round draws (Nichidai-san and Kyushu Gakuin back in 2010), and a more favorable one this year might lead to their first win at Koushien. Still, they probably won't get very far.
21st Century Bid - Masuda Shouyou (1st appearance) - C-
Masuda Shouyou was another surprising choice in my opinion, though in retrospect it was not as shocking of a selection as I first thought.
Their resume is unfortunately not very stellar. After some low scoring games in the prefectural tournament, they had to rally from behind in the semifinals to defeat Masuda Higashi 6-5, then staved off elimination twice (once in extra innings) to defeat Hamada by the same 6-5 score in 13 innings to win the Shimane title. Still, they were shutout 3-0 by Iwakuni in the first round.
Here I do not have much more information. Their manager is a very young (28) Hayato Katsuya (早戸克也), their captain is 3B Nakamoto Kouta (中本康太) and their ace is Terado Masashi(?) (寺戸雅).
But that's about all I can find.
So that covers the entire field. Now comes the wait until the draw!