I wouldn't say that all Japanese mfrs are looking to hydrogen/fool cells. Mainly Toyota.
Being the cynic that I am, I expect that the main impetus for pushing fuel cell cars has to do with the ZEV credit calculation. A HFCEV gets 9.0 ZEV credits for each car sold, and that goes a long way toward offsetting the fuel consumption from selling a lot of ICE cars. They can sell HFCEV cars at a loss and still make up the difference on the overall fleet sales.