Tobu is one of the major railway companies in Tokyo. They have the largest private railway network in the Tokyo metropolitan area. This company is also known for diversifying their business. The current largest news was the grand opening of Tokyo Sky Tree, the 634 meter-high world's tallest broadcasting tower in front of their Tokyo Sky Tree (ex-Narihira-bashi) Station in 2012.
In October of the same year, Tobu launched a sightseeing train, called Sky Tree Train, the EMU 634 series, to promote tourism to their Tokyo Sky Tree from regions along the Tobu lines. Needless to say, the 634 series was named after the height of the Tokyo Sky Tree (634 meters).
The 634 series was modified from the existing 6050 series by J-TREC Yokohama Factory. It is operated as a 4-car train consisting of two sets of 2-car trains (1M1T). The former unit numbers were MoHa 6177, KuHa 6277, MoHa 6178 and KuHa 6278; meanwhile, new numbers are MoHa 634-11, KuHa 634-12, MoHa 634-21 and KuHa 634-22. They are all high decker-cars to secure wide views, and have special seats such as "salon seats" and "pair seats".
The salon seat is like a living room set; meanwhile, the pair seat is a love seat facing the windows. The train windows of the 634 series are also special, as they are expanded to the ceiling. It means that passengers can enjoy the full view of the gangly Tokyo Sky Tree through the windows.
Official information about Tobu Sky Tree Train (in Japanese):