The Tobu N100 series (Japanese: 東武N100系, romanized: Tōbu N100-kei), branded Spacia X (スペーシアX),[3][4] is an electric multiple unit (EMU) train type operated by the private railway operator Tobu Railway on limited express services in Japan since 15 July 2023.

[5] Production of the fleet began in fiscal 2022,[6] with the first two sets, N101 and N102, being delivered from Hitachi's Kasado plant from 5 March 2023.

[11] The N100 series sets are painted in a shade of white[12] that takes influence from the color of the Yomeimon gate at the Nikko Tosho-gu shrine.

[13] The end cars are fitted with hexagonal side windows, whose frames are inspired by the Japanese "kumiko" woodworking technique.

[14] The interior consists of the following accommodations: The N100 series fleet operates between Asakusa and Kinugawa-Onsen (or Tobu-Nikko) stations on the Tobu Skytree, Nikko, and Kinugawa lines.