Scheduled for release in December 2026 by KATO

The 5000 series—an 18-meter-class, three-door train featuring longitudinal seating—debuted in 1963. It was newly built to enhance the corporate image of Keio Teito Electric Railway (now Keio Corporation) in conjunction with the relocation of the Keio Line's Shinjuku Station underground and the upgrade of the line's voltage to 1,500V. The series was assigned to the newly established limited express service and won the Laurel Prize the following year. Air-conditioned units were introduced starting with the 1968 production batch; the series played a pivotal role in the company's air-conditioning initiatives, covering both new builds and retrofitting existing stock, with a total of 155 cars manufactured by 1969. A notable feature is the variety of designs for the bogies and air-conditioner housings, which differ depending on the year of manufacture or the timing of air-conditioning retrofits. The series remained in service until 1996, having received the Keio Corporation CI logo in 1989. Following their retirement, many units were transferred to regional private railways, while three cars from the 5100 series were converted into freight trains and remained in operation until 2004.