Without being able to read Japanese, I think you have to manually enter the settings. Based on this page, I would use these settings:

incoming IMAP server imap.so-net.ne.jp, port 993, SSL/TLS security, authentication = normal password, User Name = email address

outgoing SMTP server mail.so-net.ne.jp, port 587, STARTTLS security, authentication = normal password, User Name = email address

I think IMAP is a paid service.

Dear Mozilla Support Team, Good afternoon. Thank you for your message regarding for titled topics.

Regarding the connection with so-net mail has been solved. That is amazing for me that you attached Japanese so-net documents to me, it was really sustainable a lot. After choosing POP3, I could see the Thunderbird mail this morning as the default setting. Really However, unfortunately I cannot transfer existing my Thunderbird mail profile data import to my new PC yet. If you know the reason why, plase advise it to me, as I attached screen shot. Thank you and best regards, Minoru Takimoto

I suggest you use the manual method. On the new PC, install TB and run it once so it creates a profile folder. The profile can be opened from Help/Troubleshooting Info, Profile Folder, Open Folder. Close TB but keep the profile open in File Explorer. On the old PC, open the old profile, close TB and copy the old profile folder to a USB or some other removable drive. On the new PC, close TB and delete the contents (not the folder itself) of the new profile folder, then copy in the contents (not the folder itself) of the old profile folder. Start TB, and you should see the same setup as on the old PC.

Re: Reply for updated Mozilla Support instruction about Takimoto224

Dear Manu Andino　San, Thank you for giving the advice for installing TB on my new PC. Then, accordance with your instruction, I have tried it several times, but I could not get any previous data at all. Even though, I can be abandoned to get the old profile folder, I really need the old mail address data to my new PC. So that, could do advise me to how to get the address data from the old profile folder. I need it more detailed instruction. You can see the print screen about it. It’s necessary to use Thunderbird file for me, because created it only in it. Thank you and best regards, Minoru Takimoto　Dated on Aug 17th, 21:10

To get the address books from the old profile, copy abook.sqlite and history.sqlite into the new profile, with TB closed, overwriting the existing files.