When someone such as an international student applies for permission for activities other than that permitted under the current status, what naturally comes to mind are requirements such as working for 28 hours or less per week and no activities such as adult entertainment business or store-based special sexual entertainment business. Does this mean someone who has been hired by a Japanese employer can establish a company and administer the business for 5 hours and a little more per day for 5 days per week as long as that person receives permission for activities other than that permitted under the current status?
The Minister of Justice might allow someone who applies for permission for activities other than that permitted under the current status to establish and administer a business for an extra income. However, if you work as a sole proprietor or engage in activities where it is difficult to objectively confirm working hours, you must apply for individual permit (whereas, students and dependents apply for blanket permit).
This does not mean permission is likely to be given as long as you do not work more than 28 hours per week to administer the business. You must submit at least a statement of reason and a detailed business plan like that required for a Business Administration Visa to explain the nature of the business you are wishing to run. The Minister of Justice has the entire right to decide whether to grant permission. How you convince the minister is the most important key for success.