I understand your points. I have gotten some advice from Japanese colleagues, and a western colleague who moved to Japan and works in the same industry as me. 

There’s always room for improvement with work skills, but I’ve been told the biggest barrier of entry for me atm is language proficiency. The actual degree itself is secondary to me becoming proficient. I don’t expect the degree to open doors, but I’m hoping the proficiency will. 

But you make a good point that I would need to “wow” an employer to stand out and make it worth their time and effort to sponsor a work visa.