The Seiko 5Y31-5B20 is a watch model based on the 5Y31 movement.
Parts List
| ESDW01JN01 | crystal |
| ESDW01JN | crystal |
| 32M25NN1 | crown |
| 0F210BAA3 | case back gasket |
| 0F210BAA1 | case back gasket |
| 0F210BAA | case back gasket |
| B1577C | band |
| B1600G | band - metal band |
| B1577G | band |
| B1600G-BK5G | clasp - clasp |
| B1577C-BK5S | clasp - clasp |
| B1577G-BK5G | clasp - clasp |
| 2BC100A1BAA | hand - minute hand |
| 3BA125F1BNG | others - second hand |
| 1BC070A1BAA | others - hour hand |
| 1BA070A1BNG | others - hour hand |
| 2BA095A1BNG | others - minute hand |
| 1BA060A1BNG | others - hour hand |
| 0351671 | others - winding stem |
| EB0055B01 | others - crown and stem gasket |
| 5Y315B20 | others - case back |
| 5Y315B2075 | others - case |
| 5Y315B20SA | others - case |
| 5Y315C80XG14 | others - dial |
| 5Y315C80XS14 | others - dial |
| 5Y315C90XS14 | others - dial |
| 5Y315D00XB14 | others - dial |
| 5Y315D00XG14 | others - dial |
| 5Y315D00XS14 | others - dial |
| 82820670 | others - case ring |
| A150BS | others - push pin |
| 09T13NGH | others - hour hand |
| 09T13NGM | others - minute hand |
| 2BA090A1BNG | others - minute hand |
| 2BC100A1BNG | others - minute hand |
| 10T19NGM | others - minute hand |
| 1BC070A1BNG | others - hour hand |
| 10SC27NG | others - second hand |
| 10T19AGM | others - minute hand |