Trains continue with direct service into the Meguro Line of Tokyu Corporation for Hiyoshi.

The Tokyo Metro Namboku Line has used full-height platform screen doors since its opening.

Under an agreement of both parties, the fare for this section is calculated on the Toei system for passengers travelling to stations on the Mita Line past Shirokane-Takanawa, using the Tokyo Metro system for those travelling on the Namboku Line past Shirokane-Takanawa, and on the system "most beneficial to the passenger" (presently the Tokyo Metro schedule) for travel solely on the shared section.

Under a revised proposal in 1962, the line was made independent and its construction was undertaken by the Tokyo Metropolitan Government.

There were plans for it to run to Toda, Saitama, to serve a boat-racing venue for the 1964 Summer Olympics.

However, both Tokyu and Tobu decided the following year to operate their thorough services with the Teito Rapid Transit Authority (TRTA, now Tokyo Metro) lines instead.

With no thorough service opportunities available the Tokyo Metropolitan Government began construction on the central portion of the line, leaving the plans for the Itabashi and Mita ends open for future development.

The northern 1.3 km (0.81 mi) extension (originally licensed to Tobu and later transferred to Toei Subway) was completed on 6 May 1976.