--- /dev/null
+\documentclass[a6paper]{ltjsarticle}
+%\documentclass[paper=b5j]{jlreq}
+\usepackage{luatexja-adjust}
+\ltjenableadjust[profile]
+\usepackage[pdfbox]{gentombow}
+\begin{document}
+\noindent\makeatletter
+\smash{\rlap{%
+ \kern\dimexpr-\oddsidemargin-1in-10mm%
+ \raisebox{\dimexpr-.5\paperheight+\headsep+\headheight+\topskip+\topmargin+1in}%
+ {\vrule height0mm depth.5\paperheight width 5pt\vrule height.5\paperheight depth 0mm width 5pt}%
+}}%
+aiueo \strip@pt\dimexpr0.35145980351459803\paperheight mm%
+
+\end{document}
+