個人事業税/Personal business tax as an author.

I just received this 個人の事業内容についてのお尋ね from the tax office and not sure how to proceed. I'll probably go to the tax office because I don't want to make any errors. But, anyway,

I'm an author and sole proprietor with "two" sources of income (actually one type of income):

1. Book sales. People buy my books, either from Amazon etc or from myself and I get paid royalties. Some money comes from the printer/distributor monthly and some directly from customers who buy from my website. I have no contract or agreement with this printer/distributor which is a major commercial print-on-demand company used by millions of people. I declare this as business income.

2. I have a publishing contract with a publisher in the US for my next book and I received an advance on my royalties upon signing the contract. Also declared as business income.

So, basically, my income is entirely book royalties from various sources.

So, as I see it, I'm definitely not an employee of this publishing house nor of anyone else and all my income is business income.

Have I made any errors in this basic assessment of my situation and income type?? And will I have to pay this "personal business tax"???

Thanks for your help!!!