file names

[Thomas]

Good afternoon
Using (rarely) kubuntu 15.04 on a Dell Inspiron 1545.

The other day I noticed, that kubuntu does not recognize file names with
Japanese characters in it -
and refuses to "do" anything with/to those files.
According to the computer: they do not exist.

In the file manager, the files are listed, including their size.
The same files ARE recognized on a Mint and an xubuntu system.
And naturally on my Windows machines.

What is this all about?
I the past I have NEVER had to think about whether I use Japanese or
alphanumeric characters for file names.
On ALL computers and OSs I have used.

Is there a comprehensible reason for this behavior ... and possibly a
solution?
Thank you
Thomas