According to The Nikkei, The Koto Ward Office estimates that the line would be profitable in 29 years if its fare is Yen 70 ($US 0.71) higher than that currently charged by Tokyo Metro. The central government requires a rail project to achieve profitability in 30 years to be eligible for subsidies, and the ward office now plans to develop an implementation plan by the end of this year with a view to starting the project in 2015 and beginning operations in 2025.

The new line, which will be operated by Tokyo Metro, will connect with Toyosu station on the Yurakucho Line and Sumiyoshi station, which is served by the Hanzomon Line and the Toei metro network. The line will add two new stations and also connect with Toyocho station on the Tozai Line.

The project is estimated to cost Yen 126bn to complete with the Koto Ward Office and Toyko Metropolitan government providing a third of this cost, with state subsidies set to cover another third and the remainder coming from loans provided to a semipublic entity which will handle construction.

The new line is intended to ease overcrowding on existing services and improve access to the waterfront area which is currently experiencing a major redevelopment.