Yes. However, please be aware that you cannot use your current SIM card during the period your change request is being processed (which means you will be without service until your new card is delivered to you).
* Please note that there is a 3,300-yen handling fee (including tax) for changing your SIM card size.
Please submit your request to Asahi Net.

Asahi Net English Customer Support
https://asahi-net.jp/en/contact/