Hi, if you are using SaaS, you cannot add fonts. This is related to some font license issues.
For example, Microsoft took a long time to add fonts for BarCode.
https://yzhums.com/11763/
https://yzhums.com/20231/
And according to my tests, the best font for Japanese on SaaS is "MS UI Gothic", you can have a try.
In addition, if you are the On-Premises version, or the Docker version, you can import fonts by yourself.
Hope this info will help.
Thanks.
ZHU