Japanese in HTML editor

[Convoy]

I have seen many messages here about problems displaying Japanese in
the browser, but my problem is slightly different.

The Japanese displays fine, but sometimes, and not always, when I go
back to the html code, the Japanese characters have been replaced by
what seem to be Unicode or ASCII codings, for example:

千代田区大

etc.

Is there anyway to keep the Japanese text in the code? (Well, I am
sure there must be, because this does not occur for all entries)

In case you are wondering, I want to preserve the Japanese characters
so that I can edit the code again next time, as currently, my only
option is to edit it from the graphical code, rather than the text
code (Normal tab rather than the HTML tab)

I am using English language FrontPage. Will Japanese FrontPage be any
different?

Thanks in advance