It is interesting. And it shows Japan's interest in increasing their marine capabilities. But with a little over a brigade's worth of troops of Japan's Self Defense Forces earmarked for marine training and little capabilities to move troops ashore against opposition, the word I'd use is "minimal."
Fortunately, it doesn't have a lot to do to be really important to Japan in the Senkaku Islands dispute with China:
The SDF is keeping the initial amphibious forces small because it doesn’t want to seem provocative, and because the islands it is training to recover are all fairly tiny. The SDF could buy enough AAVs to transport an entire company, but the islands are all so small a platoon could easily secure them.
As I've written in regard to our plans for a reinforced battalion of Marines in Australia, sometimes a few will do.
But it would be far better for Japan to have troops on the ground to defend the islands rather than have to retake them while the clock ticks toward a cessation of hostilities.
As important as having the ability to retake islands, Japan also needs the ability to put platoon- and company-sized elements on the islands with anti-ship and anti-aircraft capabilities. The ability to sow mines around the islands quickly would be extremely useful, too.
The ability to defend more also reduces the strain on Japan's burgeoning marine capabilities to retake lost ground by reducing what China can seize early in a militarized crisis.
