西武鉄道らしい顧客サービスの新しいありようを具現化すべく開発した次世代通勤車両。ロング・クロス転換シートの導入や、西武らしい生活路線を意識し、様々な人々に多目的に使用できる「パートナーゾーン」を開発するなど、随所に先進的な試みがなされた。
This next-generation commuter railcar was developed to embody a new way of customer service that is typical of Seibu Railway. Advanced attempts were made throughout, such as the introduction of long cross-convertible seats and the development of "partner zones" that can be used for multiple purposes by a variety of people, with an awareness of Seibu's unique lifestyle routes.