Hello Taku Shikanai,
Thank you for providing the csv file. I did some testing with the latest version of Tableau and confirm the same results you see in the image. Tableau is utilizing the Shift_JIS Characters Set to read this sample file.
To assist with this request, I suggest contact Tableau Support at firstname.lastname@example.org to determine if this is the expected behavior. The file is being read and displaying with Japanese characters however I suspect either a limitation in the text conversion or in the translation.
Thank you very much indeed for confirm my trouble!
ANd thank you very much for advices.
First,I'll try to change character set to other Japanese character.
And then contact to Tableau support!
Again,Thank you very much!!