Showa year 24 (1949), PCGS MS-65. Note the nen is now located on the right, so this is read left to right (vs. previous years). Not precisely a current coin, but this is how it is designated in the JNDA.
Showa year 28 (1953), NGC MS-65. The lettering is 'old style' script or 'kaisho'.
Showa year 39 (1964), NGC MS-65. The lettering is 'new style' block or 'gothic'.
Heisei year 20 (2008), NGC MS-66