To get the best view of Mount Fuji on the Tokaido Shinkansen, you need to sit on the right side when traveling from Tokyo toward Osaka or Kyoto. Specifically, you should request window seat E in ordinary cars or seat D in Green cars. The mountain is most visible around the 45-minute mark of the journey, particularly near Shin-Fuji Station. If you are traveling in the opposite direction (from Osaka/Kyoto back to Tokyo), you should sit on the left side, which corresponds to window seat A. For the clearest views, try to book a morning train in winter or early spring when the air is less hazy. Even with the right seat, visibility depends entirely on the weather, as the peak is frequently shrouded in clouds, so checking a local "Fuji visibility forecast" before boarding is a pro-tip for travelers.