\RequirePackage{lltjp-geometry}
+\ifdefined\ltj@stop@overwrite@primitive
+ \begingroup
+ \def\ltj@loop#1{%
+ \unless\ifx#1\@nil
+ \escapechar-1
+ \ifcsname ltj@@orig@\string#1\endcsname
+ \ifcsname ltj@@\string#1\endcsname
+ \edef\ltj@@next{\unexpanded{\global\let#1}\csname ltj@@orig@\string#1\endcsname}%
+ \edef\ltj@@temp{ltj@@orig@\string#1}%
+ \escapechar92
+ \PackageWarningNoLine{luatexja}{%
+ Restoring \string#1\space into its orignal meaning\MessageBreak
+ (\expandafter\meaning\csname\ltj@@temp\endcsname)}%
+ \ltj@@next%
+ \fi
+ \fi
+ \let\ltj@@next\ltj@loop
+ \else\let\ltj@@next\relax\fi\ltj@@next
+ }%
+ \expandafter\ltj@loop\ltj@stop@overwrite@primitive\@nil
+ \endgroup
+\fi
+
%%------------------ all done
\ltj@latex@AtEnd
\endinput
--- /dev/null
+\makeatletter
+\def\ltj@stop@overwrite@primitive{\insert\vadjust}
+\makeatother
+
+\documentclass[landscape]{article}
+\usepackage[margin=10mm,centering]{geometry}
+
+\usepackage{luatexja}
+\usepackage{breqn}
+
+\begin{document}
+\ttfamily\parindent0pt\footnotesize
+\def\chk#1{%
+ \par\medskip\leavevmode
+ \hbox to 11em{\expandafter\string\csname #1\endcsname:\hss}\
+ \expandafter\meaning\csname #1\endcsname\\
+ \hbox to 11em{\expandafter\string\csname ltj@@#1\endcsname:\hss}\
+ \expandafter\meaning\csname ltj@@#1\endcsname\\
+ \hbox to 11em{\expandafter\string\csname ltj@@orig@#1\endcsname:\hss}\
+ \expandafter\meaning\csname ltj@@orig@#1\endcsname
+}
+
+a\vadjust{\hrule height 1pt width 30pt}bc\\d
+
+\chk{/}
+\chk{insert}
+\chk{vadjust}
+\chk{raise}
+\chk{lower}
+\chk{moveleft}
+\chk{moveright}
+\chk{vsplit}
+\chk{vcenter}
+\chk{unhbox}
+\chk{unvbox}
+\chk{unhcopy}
+\chk{unvcopy}
+\chk{lastbox}
+\end{document}
+
+
+