Middle-aged family with 5-year-old son from Canada, arriving in Tokyo December 1st. Seeking navigation aid for December 2nd and 3rd, 8 AM to 5 PM. Must speak English. Help us navigate train stations to get us from our Yokohama hotel to Shibuya Crossing, on a bullet train ride, and back. Itinerary is already set.
I am pretty sure there is no bullet train to or from Shibuya crossing. There are regular local or regional trains from Yokama Station to Shibuya. Or, depending where your Yokahama hotel is located, there might be a subway line that goes through to Shibuya without a transfer. Your hotel will be able to give you step by step directions. There are also travel apps that someone may be able to recommend. I can remember how daunting the Tokyo transport network looked from afar but how relatively easy it actually was to navigate and get help.
I would contact your Yokohama hotel for assistance.
There is a bullet train, the Tokaido Shinkansen that goes from Shin-Yokahama (a different station than Yokahama station) to Tokyo station (the main train station in Tokyo.) It takes under 20 minutes and doesn't go anywhere near its top speed for this run.
From Tokyo Station to Shibuya you will need to take a combination of the Marunouchi and Ginza lines.
It's easier to get from Yokahama to Shibuya if you ditch the idea of taking the bullet train. In fact, you could get one train between stations with no changes.