The Seiko 5Y31-6A20 is a watch model based on the 5Y31 movement.
Parts List
| 270W99LN01 | crystal - crystal (inorganic) |
| 270W99LN | crystal |
| 35MK9NN1 | crown |
| 35MK9NS1 | crown |
| FE278BA11 | case back gasket - case back gasket |
| DH0100B01 | case back gasket - crown and stem gasket (4h) |
| DH0100B0 | case back gasket |
| 86590190 | crystal gasket |
| 86590970 | crystal gasket - plastic gasket for crystal |
| ZPA30G | band - leather band |
| ZPA30S | band |
| ZPJ14G | band |
| 3AA125F1A6S | others - second hand |
| 3AA125F1ANG | others - second hand |
| 12SC39T2 | others - second hand |
| 12SC39T1 | others - second hand |
| 11SC43T1 | others - second hand |
| 1BC080A1BAA | others - hour hand |
| 2BA120A1BNG | others - minute hand |
| 10T45AGM | others - minute hand |
| 2BC105A1BAA | others - minute hand |
| A150BS | others - push pin |
| 0351671 | others - winding stem |
| 82733090 | others - case ring |
| 5Y316A20 | others - case back |
| 5Y316A2061 | others - case |
| 5Y316A2075 | others - case |
| 5Y316A20XG14 | others - dial |
| 5Y316A20XS13 | others - dial |
| 5Y316A40XS14 | others - dial |
| 11T05AFH | others - hour hand |
| 12T07NGM | others - minute hand |
| 2BA120A1BNS | others - minute hand |
| 12T07NSM | others - minute hand |
| 1BA080A1BNG | others - hour hand |
| 12T07NGH | others - hour hand |
| 1BA080A1BNS | others - hour hand |
| 12T07NSH | others - hour hand |