Automatic train control (ATC) was activated on the Marunouchi Line on February 27, 1998, which allowed for an increase in the maximum operating speed limit from to . This was followed by Train automatic stopping controller (TASC) which was introduced in November 2002, along with Automatic train operation (ATO) which was introduced on the main segment of the Marunouchi Line on December 27, 2008. The platform-edge doors at Hōnanchō Station, the terminus of the Hōnanchō Branch, were lengthened to allow six-car trains to use the station, with work starting in 2013, which enabled through trains to and from Ikebukuro to start operating all the way to Hōnanchō from fiscal 2017.