Who likes to ride against the wind? That's what I thought. Hills? I can live with them and have climbed 1500m passes, which only amounts to an hour or several of effort. Wind... Wind never lets up. That's why you need to hop the train, if you can, or get a spouse to take you upwind to ride back home, or ride across N.America west to east. This is especially important in Japan, because all of the unimpeded and traffic free routes near cities are along the top of levées, and there is no shelter from wind up there.
In Japan, you need a rinkou-bukuro: 輪行袋. You must bag a bike to take it by train in Japan, and not in rush hour. I am partial to the Tioga Cocoon, as this bag is cheap and light. A hint: on a standard Japanese train, the very front and the very rear of the trains each hold a driver's compartment, and have enough wall-space to lean your bike. Nowhere else.
However you get upwind, you have to know the wind forecast. I love surfers and their websites! The other day I snatched a 30km/hr tailwind and was able to do double the speed downwind than I would have been able to do upwind. And no, riding into the wind is not exercise, it is an exercise in grinding away knee cartilage.