kai.grossjohann@gmx.net (Kai Gro.AN_johann) writes:

> When you do C-x C-f of a nonexisting file, then kill/yank the
> Japanese line from the HELLO file there, then C-x RET f utf-8 RET,
> then C-x C-s, what do you get?
>
> I get the following message:
>
> /----
> | Select one of the following safe coding systems, or edit the buffer:
> |   shift_jis euc-jp iso-2022-7bit compound-text-with-extensions
> | Or specify any other coding system
> | on your risk of losing the problematic characters.
> \----

I get the same.

> Why doesn't it allow me to use utf-8?

This works fine:

(decode-coding-string
 (encode-coding-string "Japanese ($BF|K\8l(B)" 'utf-8) 'utf-8)

So, it seems to suggest that Emacs *is* able to encode it as UTF-8.