[5] In 2018, Toei ramped up its plans and announced that 13 new trainsets with the same designation numbers as the 13 that are replaced would be introduced to service.

[6] These new models are formed as 8-car sets[7] made by Kinki Sharyo and classified as 6500 series.

[9] The 3rd batch of 6300 series trainsets continued their service on the Mita Line upon being upgraded to enable compatibility with the Sōtetsu Line, by introducing digitized communications equipment and the ATS-P system.

[10] With Mita Line trainsets extending to 8 cars, Sōtetsu underwent preparations to enable compatibility with 8-car trains.

However, trains would not be allowed to run through on the Seibu Yūrakuchō and Ikebukuro Lines.

[14] Through the end of 2022, various trainsets from Tōkyū, Sōtetsu, Tokyo Metro, Toei,[15] and Tōbu conducted tests[16] along the now completed segment of this line and the Sōtetsu Shin-Yokohama Line between Hiyoshi and Hazawa Yokohama-Kokudai.