Starting to plan a trip to Japan in late March 2023. Looking at a visit to see the area around Mt Fuji. The plan is to leave Tokyo in the morning and spend the night in Kawaguchiko. Will the Sightseeing Bus be operating that early in the year?
We will then be traveling west to Himeji but it appears that most of the transportation goes back to Tokyo to use the bullet train.

I was in Kawaguchiko on Friday. You absolutely need to take the ropeway up for the magnificent views. It is on the red line bus. There are multiple color coded buses. You can find operating dates on the web. Pay fares with an IC card (Suica works). They had signs saying you could use Visa tap and pay, first time I saw that anywhere.

Do use luggage shipping (takkyubin) to send your main luggage on to Himeji and just take what you need for the overnight and next day to Fujigoko. I was smh, too often, seeing tourists wheeling around enormous suitcases. Please don't be one of them.

There is a JR l'ex from Shinjuku to Kawaguchiko station, all reserved seats, and you need to book in advance. Departures were at 8:30 and 9:30. The other option is JR to Otsuki and then the Fujikyu rail to K-go. If you go that way then you get a ticket for 1175 and also pay 400 for the express train which will be waiting.There were quite a few people who had to pay that on the train. Better to get it at the machine and have ticket and express ticket ready for the conductor.

I think there is a bus to Shizuoka and another way to get to Shin Yokohama. Another way, bus, more time, would be to go thru Hakone to get the shinkansen at Odawara.I think the route goes via Gotemba. You could do the Hakone Loop if you have the time and interest.

Shin Yokohama is a stop for all shinkansen. Shizuoka and Odawara only have Kodama and infrequent Hikari shinkansen. The Kodama (a shinkansen local) would make a lot more stops than the Hikari and you would want to change at Nagoya. You want to book reserved seats in advance (because most seats will be snagged upstream).

If you do go via Tokyo then look for limited express trains from Otsuki that go on thru to Tokyo. Or that JR L'ex from Kawaguchiko to Shinjuku might go on to Tokyo station. Connection at Shinjuku might be only crossing the platform. Be sure to ask about the platforms when you get your seat reservations.