When the 7th generation started 3 major things happened that caused the coma for the japanese market.
1 The wii was successful while most developers where centering on HD or hanhelds. If the market would have known (impossible) and put their games on the wii then things would probaly have been different.
2 Sony messed up big time with price and arrogance and the third reason
3 Microsoft striving to get into the market got most of the games that would have sold well on either the wii or ps3 (japanese games RPGs and other well known series). And because the xbox360 didn't do well in Japan these game which should have been the base for a console to be a success in Japan actually didn't sell well. Causing both the wii and the ps3 to flounder without more software and creating a situation no games no console sells no console sell no games.
Now this coma i hope can be come out of if, Sony or Nintendo succeed greatly enough in all the markets. And looking at the wii u performance it seems the ps4 is the only chance.
Lets hope the PS4 is greatly successful or this coma could become death for console gaming in Japan.