[5] In preparation for the opening of the Hokkaido Shinkansen, the Seikan Tunnel (Kaikyō Line) and associated approaches (approximately 82 km or 51 mi in total)[6] were converted to dual gauge, with both the Shinkansen 1,435 mm (4 ft 8+1⁄2 in) standard and 1,067 mm (3 ft 6 in) narrow gauge tracks.

In January 2024, JR Hokkaido announced that the speed would be raised to 260 km/h (160 mph))[11] during major holidays going forward.

In May 2019, JR Hokkaido announced that it had requested permission from the MLIT to increase the speed limit on the 212 km (132 mi) of new track to be constructed between Shin-Hakodate-Hokuto and Sapporo to 320 km/h (200 mph).

[15] Based on the E5 series trainsets operated by JR East since 2011, the order for 40 vehicles cost approximately 18 billion yen.

[16] The vehicles feature the usual upper green and lower white livery, with a purple stripe in the middle.

Green class features cream-colored walls representing the local dairy industry and carpet with a drift-ice motif.

Gran class features dark blue carpets, said to be modeled after the shimmering lakes and bodies of water along the route.

On 1 November 2014, a ceremony was held at Kikonai Station to mark the completion of track-laying for the line between Shin-Aomori and Shin-Hakodate-Hokuto.

[20] Test-running south of Oku-Tsugaru-Imabetsu commenced on 21 April 2015, with the first train reaching Shin-Aomori Station from the north in the early hours of 24 May.

[4] There is potential for the opening date to be revised in either direction, and a further announcement will be made after discussions at a panel of experts which will commence in January 2025.