I posted a video on youtube almost 7 years ago, of how to check your firmware version on the PCM-M10. Mine is 1.00 and I have not ever heard of any other version.
If anyone gets the Japanese version, there's a Language setting buried in the menu of my USA black model:
press the Menu key to enter menu mode
press 7 clicks on the Fast-Reverse button to Detail Menu
press the Play Button to choose it
press 3 clicks on the Fast-Reverse button to Language menu
use FF/FR to select language from the menu
press PLAY to choose it
press 2 clicks of the Menu key to exit all menus
Mine only lists English, Spanish, French, but when it's in those languages, the word (Language) in the menu is listed along with Idioma and Langue for clarity.
Idioma (Language) - Español
Langue (Language) - Français
Do you have Firmware Version 1.00? Hold the STOP key to find out.
To find out the firmware version of your Sony PCM-M10 solid state audio recorder, power the machine up, then press and hold the STOP button. After about 5 seconds,, the screen will display the current firmware version. My PCM-M10/BLC is a black color model, from USA. It reports Firmware Version 1.00. If yours differs, please post here.
https://youtu.be/58y_wbGgq3gThe M10 is a great recorder. You will love it.
(SNIP)
Sony may have changed the firmware in the later Japanese M10's so it may have the language option in the one you bought.
If you bought a US/EUR version one, or you know Japanese, please disregard everything I wrote in the second part of the post
Enjoy your new recorder!