The Tobu 634 series (東武634系, Tōbu 634-kei) is an electric multiple unit (EMU) train type operated in Japan by the private railway operator Tobu Railway since 27 October 2012.

[1] The 634 series designation was chosen as it can be read as "Musashi" in Japanese, and coincides with the height in metres of the Tokyo Skytree.

[3] The two two-car sets are based at Shin-Tochigi Depot, and are formed as shown below with the Mc car at the southern end.

The two former 6050 series sets were rebuilt at J-TREC's Yokohama factory, and delivered to Tobu at the end of September 2012.

[1] The former Skytree Train limited express services were discontinued from the start of the revised timetable on 21 April 2017.