The and are electric multiple unit (EMU) train types operated by the private railway operator Seibu Railway in Japan.
The 101 series began service in 1969, in conjunction with the opening of the Seibu Chichibu Line.
The New 101 series features changes in design. The 301 series is based on the New 101 series, and were formed as eight-car sets.
The Chichibu Railway 6000 series trains were rebuilt from former Seibu New 101 series trains. Sangi Railway operates former New 101 series trains as Sangi Railway 751 series. Former Seibu New 101 series trains were also transferred to Ryutetsu, becoming Ryutetsu 5000 series trains.
In 2018, one set received a livery resembling the Ohmi Railway 100 series. Other livery variations include a set in Izuhakone Railway livery, and a set in red and beige livery.