It needs its wind manufacturers, assuming they are not on that level yet, to hook up with manufacturers that produce 5 to 7 MW offshore turbines.

In the USA and in Europe there is development and experiments in floating wind.
Japan should be invited to join those projects, go thru a learning curve, boost the projects with their knowledge and expertise and bring home the lessons learned. From there they have apply in big on GW scale (or not at all)

At home in Japan, they need to look now at where to locate these offshore parks and how to reinforce the E-Grid, from backbone to the chosen locations. Plan out gas peakers or storage to deal with winds intermittancy. Than with that homework done they can skip our implementation hassles an directly achieve wind penetration values of 60% or more.

That kind of help is needed and not the few dime from the US for a micky mouse project. (Although it seems to be their decision to spent a part of the fund on that project.)