According to The Wrestling Observer, TNA is essentially getting Sanada for free, as Wrestle-1 is currently paying his regular salary to work in TNA.
As far as Wrestle-1 is concerned, The Great Muta believes Sanada working for TNA and holding the X-Division title will help make him a much bigger star in Japan.
Back when Sanada dropped the X-Division title, it was believed he would be returning to Japan full-time by the end of the year, but now there is talk of signing him to a joint TNA/Wrestle-1 contract which would see him work primarily in TNA and appear at big Wrestle-1 events.
If a joint deal is in fact the route the companies plan to take with Sanada, then he would have to be somewhat protected in TNA story lines so he can remain a big star in Japan. It's said The Great Muta views Sanada as a future top guy in Wrestle-1.