@janl It’s a fairly long way to go from Tokyo as a day trip, and you could in theory combine it with some kind of Fuji-enjoying excursion. But as the test run schedule is only published a few days ahead, it’s difficult to plan accommodation. But you have that problem anyway with Fuji and the weather. (Speaking from experience of getting soaked & freezing in heavy sleet while visiting Hakone one April…)
The attached museum is interesting enough, but not worth a trip without test runs.