# Sotetsu 20000 series

The Sotetsu 20000 series (相鉄20000系) is an electric multiple unit (EMU) commuter train type operated by the private railway operator Sagami Railway ("Sotetsu") in Japan in the Tokyo area since February 2018. Ultimately intended to be used on through-running services between Sotetsu and Tokyu Corporation lines commencing in late fiscal 2022, the first train entered revenue service on 11 February 2018, replacing a 7000 series set.
Eight-car sets designated as 21000 series were announced in April 2021, the first of which entered service in September 2021.

## Design

The fleet of ten-car 20000 series trainsets is being built by Hitachi at its Kasado Factory in Kudamatsu, Yamaguchi. Externally, the trains carry the "Yokohama Navy Blue" corporate livery introduced for refurbished 9000 series trains.

## Formation
### 20000 series

The trains are formed as ten-car sets, as follows, with five motored ("M") cars and five non-powered trailer ("T") cars, and car 1 at the Yokohama end.
| Car No. | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 |
| Designation | Tc2 | M1 | T1 | M2 | M3 | T2 | M4 | T3 | M5 | Tc1 |
| Numbering | 2010x | 2020x | 2030x | 2040x | 2050x | 2060x | 2070x | 2080x | 2090x | 2000x |
| Weight (t) | 29.9 | 31.7 | 29.8 | 31.1 | 31.2 | 26.9 | 31.7 | 29.1 | 31.1 | 30.0 |
| Capacity (seated/total) | 45/133 | 51/144 | 51/143 | 51/143 | 51/143 | 51/143 | 51/143 | 51/143 | 51/143 | 45/133 |

### 21000 series

The trains are formed as eight-car sets with four motored ("M") cars and four non-powered trailer ("T") cars, and car 1 at the Yokohama end, as follows.
| Car No. | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
| Designation | Tc2 | M1 | T1 | M2 | M3 | T2 | M4 | Tc1 |
| Numbering | 2110x | 2120x | 2130x | 2140x | 2150x | 2160x | 2170x | 2180x |
| Weight (t) | 29.9 | 31.7 | 29.8 | 31.1 | 31.7 | 29.1 | 31.1 | 30.0 |
| Capacity (seated/total) | 45/133 | 51/144 | 51/143 | 51/143 | 51/143 | 51/143 | 51/143 | 45/133 |

## Interior

Passenger accommodation consists of longitudinal bench seating with grey moquette seat covers. Each car includes a space for wheelchairs and pushchairs.
* A car interior in February 2018
* Universal design priority seating
The colour temperature of the interior LED lighting is adjusted automatically according to time of day and season as follows (hues shown are illustrative only).
| Season | Time of day | Time of day | Colour temperature [K] | Intensity [%] |
| Spring (1 April - 30 June) | Early morning | 02:01:00 - 06:59:59 | 4400 | 90 |
| Spring (1 April - 30 June) | Morning peak | 07:00:00 - 09:59:59 | 5000 | 90 |
| Spring (1 April - 30 June) | Daytime | 10:00:00 - 15:59:59 | 4400 | 90 |
| Spring (1 April - 30 June) | Evening | 16:00:00 - 17:59:59 | 4400 | 90 |
| Spring (1 April - 30 June) | Night | 18:00:00 - 02:00:59 | 3000 | 100 |
| Summer (1 July - 30 September) | Early morning | 02:01:00 - 06:59:59 | 5000 | 90 |
| Summer (1 July - 30 September) | Morning peak | 07:00:00 - 09:59:59 | 5000 | 90 |
| Summer (1 July - 30 September) | Daytime | 10:00:00 - 15:59:59 | 5000 | 90 |
| Summer (1 July - 30 September) | Evening | 16:00:00 - 17:59:59 | 4400 | 90 |
| Summer (1 July - 30 September) | Night | 18:00:00 - 02:00:59 | 3000 | 100 |
| Autumn (1 October - 31 December) | Early morning | 02:01:00 - 06:59:59 | 4400 | 90 |
| Autumn (1 October - 31 December) | Morning peak | 07:00:00 - 09:59:59 | 4400 | 90 |
| Autumn (1 October - 31 December) | Daytime | 10:00:00 - 15:59:59 | 4400 | 90 |
| Autumn (1 October - 31 December) | Evening | 16:00:00 - 17:59:59 | 3800 | 100 |
| Autumn (1 October - 31 December) | Night | 18:00:00 - 02:00:59 | 3000 | 100 |
| Winter (1 January - 31 March) | Early morning | 02:01:00 - 06:59:59 | 3300 | 100 |
| Winter (1 January - 31 March) | Morning peak | 07:00:00 - 09:59:59 | 3800 | 100 |
| Winter (1 January - 31 March) | Daytime | 10:00:00 - 15:59:59 | 4400 | 90 |
| Winter (1 January - 31 March) | Evening | 16:00:00 - 17:59:59 | 4400 | 90 |
| Winter (1 January - 31 March) | Night | 18:00:00 - 02:00:59 | 3000 | 100 |

## History

Details of the new trains were officially announced in June 2017. The first train set was delivered from the Hitachi factory in Kudamatsu, Yamaguchi, in late July 2017.
Originally scheduled to enter revenue service in December 2017, scheduled service entry was subsequently postponed until 11 February 2018.

### 21000 series

An order for a shorter version of the 20000 series was announced on 28 April 2021. These eight-car sets will be designated as 21000 series, and are to be operated through to lines of Tokyu Corporation. The first 21000 series set entered service on 6 September 2021.
As of April 2023, nine 21000 series sets have been built.