[5] However, as of 2022, the route of the segment east of Takeo-Onsen to Hakata via Saga has yet to be determined, with construction yet to commence.

[7] For the foreseeable future, the Relay Kamome limited express service will continue to provide a connection to Hakata.

[15] With the start of the service in September 2022, trains were operated by a fleet of four 6-car JR Kyushu N700S series trainsets.

[22] In 1985 Japanese National Railways published a map of the line that ran via Haiki in Sasebo.

[24] In 2002, the Japan Railway Construction, Transport and Technology Agency (JRTT) applied for permission to build the line between Takeo-Onsen and Nagasaki in Super Tokkyū standard.

Debate over the final section between Isahaya and Nagasaki continued for several years, before construction was approved by the government.

(Shinkansen trains have motors on axles in every car[33]) However, technical issues resulted in the cancellation of the GCT, requiring the consideration of other options.

[34] The current plan is to continue using the existing narrow gauge track with a cross platform interchange at Takeo-Onsen Station until the finalization of the remaining section to Shin-Tosu.

[37] There is also the issue of the status of the conventional Nagasaki Main Line after the construction of the West Kyushu route.

Following the decision not to use GCTs, Nagasaki Prefecture pushed for the remaining segment to be built in Shinkansen standard on the premise that it offers better convenience and shorter travel time, while Saga Prefecture opposes building in Shinkansen standard as it will need to pay a significant part of the budget despite there being no substantial change in travel time compared to preexisting services.

[38] On 5 August 2019 a committee in the governing party decided that the segment should be built in Shinkansen standard.

On 28 October 2019 Saga Prefecture and the Ministry of Land, Infrastructure, Transport and Tourism agreed that the two sides should continue holding discussions on this matter.

[41] As of September 2022, the opening of the segment between Takeo-Onsen and Hakata remains unknown as no constructions have been approved or initiated.