Not necessarily more money for them, more money for the agents. These vultures often keep waaaaay more than 50% of the share. I heard it can even be up to 80%. Which in turn increases the cost of shooting, since agents will inflate the price whenever they can -- in a way, not that dissimilar to what you can find in football with the FIFA agents.
Agents are also a nightmare to deal with, I got the confirmation thanks to a foreign acquaintance (an American guy living in Osaka) who used to shoot AV in Japan -- for a small company called Arrows if my memory serves me well.
Now, if you make direct contacts with 'free models' via their online presence (FB, Twitter etc.) it's an entirely different story. The bubble burst, less money than in the past, lots of competition etc. I'm not saying it's easy, and one definitely must be able to read/write/speak Japanese, but it's more do-able.
Be polite, take time to introduce yourself and your project, ask them about their fees and start from there.
Anyway, on a personal level, I'm really not sure I would base a AV company in Japan nor release the videos on the Japanese market. Having to deal with the necessity to censor/mosaic the footage must be a time-consuming nightmare.
Actually, after discussing with a couple of Japanese models on Model Mayhem, it seems that some of them prefer when the footage is not released in Japan.