The Nishikyushu Shinkansen (BV, Nishikyūshū Shinkansen or "West Kyushu Shinkansen") is a future shinkansen line, which will run to Nagasaki. In the future, the line is expected to connect Nagasaki with Fukuoka's Hakata Station, but when initially opening on September 23, 2022, it will be isolated from the rest of the high-speed train network and operate only between Takeo Onsen and Nagasaki.

Limited express relay trains will run between Hakata and Takeo Onsen, providing seamless connections to the shinkansen at Takeo Onsen, where trains will be lining up on opposite tracks of the same platform for easy transfers. It is not clear when and if the remaining section between Takeo Onsen and Hakata will be completed.

The Kamome will be the only train category along the Nishikyushu Shinkansen, while the limited express trains between Hakata and Takeo Onsen will be called "Relay Kamome". The Kamome will use 6-car train sets that do not have a Green Car, but reserved seating will come in rows of 2x2 seats which are almost as comfortable as Green Car seats. Non-reserved seating will come in rows of 3x2 seats. Many trains will stop at all stations along the line, while others will skip one or two stations.

Note: For simplification, some rare train compositions are omitted.