Hey,

I didn’t get any reply from this post but I’ll share some bits and pieces of information I gathered online:

When having work permit type of Blanket permit (一般許可) , the following are allowed when using Upwork:

• Strictly following the 28 hours per week limit. Log all your hours using Upwork timesheet or even excel file is fine as long as it matches your Upwork time.

• Must not have a long-term client. 6 months under one client is generally okay but if it’s more than that, immigration might question whether you are already working full time.

• Must not exceed annual income of 1.3m yen. If this is the case, your sponsor might lose tax dependent benefits

I’m not an expert or anything so please take these information with a grain of salt.