if you need this data for historical research (e.g., studying how micro-businesses communicated during the early pandemic), your best sources are:
If you are looking for specific niches using free email providers, use these search strings: site:.jp "gmail.com" "manufacturing" site:facebook.com "hotmail.com" "Tokyo cafe" "contact" "@yahoo.co.jp" industry:fashion 3. Social Media & Professional Platforms
If you are trying to reach Japanese companies for business development, skip the public domain lists and try these "white hat" methods:
By 2020, @hotmail.com was largely dead in the Japanese corporate world.
The keyword asks for – but today (2024-2026), these addresses are likely dead or abandoned .