I find something interesting about the General elections in Japan.
I notice that even in normal elections (LDP landslides), Aichi stays pretty reliably Democrat for the most part, with them winning nearly half the seats a lot of the time, and historically sweeping the prefecture. I have no clue why, and I've tried looking into it, but not really finding anything.
The basic answer is that Nagoya is a more manufacturing-focused (especially automobile manufacturing) urban area, in contrast to Tokyo and Osaka, which are more focused on knowledge industries. Therefore, Nagoya is relatively fertile ground for the DPJ's soft center-left and broadly pro-union positions as well as for its history of social democratic parties that are the ancestors of the DPJ. All of the big cities have a more tenuous relationship with the LDP than the countryside, but Tokyo and Osaka are less connected to union politics and historical support for social democratic parties.
This does not mean (unlike in the West, especially the US) that Nagoya is poor. Aichi has higher per-capita income than Osaka, for example (though much lower than Tokyo, which is much wealthier than anywhere else).
I suspect that the fact that Nagoya is a much more recently prominent urban center than Osaka-Kyoto and Tokyo, having only become significant in the late 19th century, plays a role as well, with fewer culturally conservative voters (of the sort who think Japanese imperialism was not such a bad thing) as a result, but this is harder to suss out.
