\usemodule[art-01]

\enabletrackers[scripts.*]

\definefont[testfont][ipaexm.ttf][script=kana,language=jan]

\startTEXpage
    \startformula test \stopformula \par
    \testfont \startscript[nihongo]\ruledhbox{漢字\hskip 2cm 文書}\stopscript\par
    \testfont \startscript[nihongo]\ruledhbox to 7cm{漢字\hfill 文書}\stopscript\par
    \testfont \startscript[nihongo]\ruledhbox{漢字文書}\stopscript\par
    \testfont \startscript[nihongo]\ruledhbox{漢字 文書}\stopscript\par
    \testfont \startscript[nihongo]\ruledhbox{漢字\kern 2cm 文書}\stopscript\par
    \testfont \startscript[nihongo]\ruledhbox{\hskip 2cm 漢字文書}\stopscript\par
\stopTEXpage

\stoptext
