As a starting point for your research, please refer to the following information about hosting in Osaka as well as general information about hosting in Japan (all links lead to external sites in Japanese).
You can refer to "About the Provision and Use of Minpaku (Private Lodging) Facilities", published by the City of Osaka. We recommend consulting a lawyer for legal advice about interpreting and applying laws and regulations.
The above information is not comprehensive, and you may be asked to meet other conditions or provide more paperwork depending on the situation. If you have questions or concerns about a law or regulation and how it applies to you or your property, please contact your local government agency directly or consult a lawyer for legal advice.