Where Is This Happening?
Japan is an island nation made up of four main islands. Most international travelers spend their time on Honshu, the largest island, where you will find:
These cities are connected by the country’s most famous high-speed rail lines and form what is often called the “Golden Route” for first-time visitors.
The new initiative, however, takes place on a different island: Kyushu, which lies southwest of Honshu. Kyushu is known for hot springs, volcanic landscapes, and a slower, more regional atmosphere compared to Tokyo or Kyoto.
The free ticket applies to the Shinkansen route between:
The journey takes about 90 minutes and normally costs around 11,500 yen, roughly 75 USD.

AloJapan.com