The Seiko 5Y31-5120 is a watch model based on the 5Y31 movement.
Parts List
| RECN12JN01 | crystal |
| RECN12JN | crystal |
| 30MA6NA1 | crown - crown |
| 30MA6NH1 | crown |
| 0G0055B0 | case back gasket |
| 0G0055B01 | case back gasket - crown and stem gasket |
| 0H2600N01 | case back gasket - case back gasket |
| ZMA10G | band |
| ZMA09G | band - leather band |
| ZMJ12G | band - leather band |
| 07SC02NG | others - second hand |
| 0351670 | others - winding stem |
| 5Y315120 | others - case back |
| 5Y31512025 | others - case |
| 5Y3151202N | others - case |
| 5Y315120HE | others - case |
| 5Y315370XS19 | others - dial |
| 5Y315380XG14 | others - dial |
| 5Y315380XS14 | others - dial |
| 5Y319 | others - machine code |
| 82800460 | others - case ring |
| A160BS | others - push pin |
| 08TE2NGM | others - minute hand |
| 08T38FGM | others - minute hand |
| 08T46NAH | others - hour hand |
| 08T12AGH | others - hour hand |