I stopped briefly at the Mirai table at the Long Beach motorcycle show, and I did lift up one of their batteries. If anything, it was lighter than a Shorai - it felt like an empty case. I even joked with the man behind the table that it was only a display piece and not a real battery - he begged to differ.
I have not been able to find much on the web in the way of discussion of these batteries. Anybody have one, or know someone who does?
Not so easy to search on Google - I tend to get stuff like the link below - fun to read but nothing to do with batteries. I did at least learn that the words Shorai and Mirai are related words in Japanese.