Hello, maybe you didn't explain the question right.
Do you want to be a consultant? or do you want to start an online business?

If you want to start an online business selling Japanese products online you just need a website with shopping cart, a payment gateway that is trustworthy to consumers and access to logistics like FedEx or DHL. If you need a website built for you, you can get in touch with my team at www.Unthink.me and we can see if we can help you with what you need. If you are trying to be a consultant for ecommerce, then I would say start messing around with ecommerce, get yourself a website, become successful running that online store and then leverage your experiences with others wanting to start an ecommerce business.

if you are new to e-commerce and online business, you should not set up a consultant business on online e-commerce business.
End of the answer.

Amazon. Simplifies and eliminates all the things you don't want to be distracted by and let's you focus on your business. I recently helped a guy in Slovenia do essentially what you are trying to do.