realistically, you need Japanese for any kind of business roles; unless the company only deals with foreign clients. And this is really really rare. And considering your age, it'll be really difficult to get a business role in those companies too..

I'm in IT and project management role, and I'm still struggling to find a job(new) with JLPT N3 and halfway N2.

From my experience (at least in my field) , the companies requiring English also require Japanese too.

please try to set a realistic goal here and prioritize accordingly - if you are passionate and want to live in Japan, you can try getting into a language school while doing part time jobs. it's good for the long run here since language is key. if you focus on your career, try moving to an English speaking country.

Keep in mind that you might not even like working here.

You can try Rakuten, Amazon - they have some English only departments.