Doctor Yellow

[3] Doctor Yellow trains make three round trips between Tokyo and Hakata Station every month.

The original color scheme of yellow with a blue stripe (applied to the Class 921 track-recording cars) was created by reversing the colors (blue with yellow stripe) used by track-recording cars on Japan's 1,067 mm (3 ft 6 in) narrow-gauge railways.

Because the schedule for this train is not made public, witnessing a Doctor Yellow in operation is a matter of chance.

[4][3][5] Railfans have set up websites and social media accounts to predict Doctor Yellow's arrival dates and times at stations along the route.

They are scheduled to be replaced with commercial N700S Series Shinkansen trains that incorporate inspection and observation equipment.