Should an individual developer selling a paid add-on register as Individual or Company in Microsoft Store?

I am an individual developer residing in Japan and developing a WPF desktop application. I have not incorporated a company and do not currently operate through a registered company or organization.

I plan to publish the Windows application on the Microsoft Store free of charge initially. Later, I am considering offering Google Calendar and personal Outlook.com calendar integration as a one-time paid add-on priced at approximately JPY 500.

Microsoft's current documentation describes the developer account types as follows:

• Individual: Independent developers whose Store distribution is not related to their business, trade, or profession, as well as small-scale creators developing content for non-commercial purposes, such as hobby or personal projects.

Company: Organizations, businesses, independent developers, and freelancers whose Store distribution is related to their business, trade, or profession.

Reference:

Open a developer account in Partner Center

I would appreciate clarification on the following questions:

Does an individual developer who has not incorporated a company need to register for a Company developer account merely because a one-time paid add-on will be offered?

May I register for an Individual developer account if the application and add-on are published and sold under my personal name?

If a Company developer account is required, which business verification documents are accepted from an individual or sole proprietor in Japan? For example, would a sole proprietorship notification or a Japanese tax return be accepted?

For Company registration, are a privately owned domain and an email address using that domain mandatory?

The documentation states that an Individual account cannot later be converted to a Company account. Therefore, I would like to confirm the correct account type before beginning the registration process.

I already tried to contact Partner Center support, but because I have not yet created a developer account, I could not access an appropriate support workspace. I was then directed here by a moderator on Microsoft Q&A Japan.