[1] It was introduced by JR East on 9 July 2005 to replace the aging 403 and 415 series EMUs running on the Jōban Line from Ueno Station in Tokyo.

The stock is a dual-voltage (1,500 V DC & 20 kV AC) development of the DC-only E231 series suburban EMU design, and can run at speeds of up to 130 km/h (81 mph) in service.

[3] The original ten-car sets delivered without bilevel Green cars were formed as follows.

In September 2014, an additional ten-car set, K423, was delivered from the J-TREC factory in Yokohama, four years after construction of the original fleet had ceased.

[9][10] To celebrate the 60th anniversary of the Katsuta Depot, set K451 entered service on 5 November 2021 in a wrapping reminiscent of the livery of the 401 series trains.