Files that are not specific to Japanese pTeX have been installed.
Now, you need to install japanese/ptex, which provides files necessary
for Japanese processing.

Note that the files installed by the ptex port can process all three
character codes, i.e. EUC, JIS, and Shift-JIS by specifying a
command-line option at runtime.  You can specify the default character
code if you are installing it using the port.