One way to do this, but before the mails arrive, is to use a service like IFTTT or Zapier that can both read your mails that match a search and write to Google Sheets. Then you can configure them to save any mails that match the criteria automatically. However, that would be for future mails only.
You can definitely make a Python script do this using the Gmail and Sheets API libraries to do this or use Google Apps Script to do it. ChatGTP and/or Claude can probably write the code for you to do it if you know enough programming to understand and debug it.
If you used the kanji names of the cities and towns it would be a lot more realistic.
I’ve lived in Japan since 1988 and this just seems like a list of jibberish to me. Japanese city names are, like English city names, made up of meaningful components i.e. Newbridge, 新橋,しんばし, Shinbashi. So there is nothing to get a hook on. It’s just syllables.
Try it with 2000 English city names and you will get the same quality of output.
I live on the Miura peninsular not too far from William Adams fiefdom. It’s possible to walk up the hill from Anjinzuka Station (The navigator’s hill) and see his and his wife’s grave.