Hi, there
This could be an interword space problem.
I don't know if this is what you seek.
But this is what I get via \spaceskip
3 lines with % remarks are new.
Wait for a couple of days to see alternatives from others.
\begin{document}
%
\def\CJKmovesymbol#1{\raise.35em\hbox{#1}}
\def\CJKmove{
\let\CJKsymbol\CJKmovesymbol
\let\CJKpunctsymbol\CJKsymbol
}
=E6=A8=99=E6=A5=B7=E9=AB=94=EF=BC=9A
\spaceskip=3D1em % setting space skip
\rotatebox{-90}{\fbox{
\begin{minipage}{10em}
\CJKfamily{kaiv}\CJKmove
=E6=B8=AC=E8=A9=A6test\_=E6=B8=AC=E8=A9=A6test=EF=BC=8C\\
=E6=B8=AC =E8=A9=A6test,=E6=B8=AC =E8=A9=A6test=E3=80=82 % insert a s=
pace to take effect
\end{minipage}}
}
\spaceskip=3D0em % re-gain original skip
\CJKfamily{nming}
=E6=96=B0=E7=B4=B0=E6=98=8E=E9=AB=94=EF=BC=9A
\rotatebox{-90}{\fbox{
\begin{minipage}{10em}
\CJKfamily{nmingv}\CJKmove
=E6=B8=AC=E8=A9=A6test\_ =E6=B8=AC=E8=A9=A6test=EF=BC=8C\\
=E6=B8=AC=E8=A9=A6test, =E6=B8=AC=E8=A9=A6test=E3=80=82
\end{minipage}}
}
\end{document}