\newlength\kanjicharwidth
\settowidth{\kanjicharwidth}{あ}

\newlength\kanjicharheight
\settoheight{\kanjicharheight}{あ}

% in 10pt/jbook environment:
% kanjicharwidth=9.62216pt(= Cwd)
% kanjicharheight=7.77588pt

\setlength{\intextsep}{3.0\kanjicharheight}
\setlength{\textfloatsep}{3.0\kanjicharheight}

\newlength\defaultleftmargin
\setlength{\defaultleftmargin}{2.0\kanjicharwidth}

\newlength\defaultrightmargin
\setlength{\defaultrightmargin}{2.0\kanjicharwidth}

\newlength\defaulttopsep
\setlength{\defaulttopsep}{2.0\kanjicharheight}

\setlength{\voffset}{-20mm}
\addtolength{\textheight}{30mm} %
\setlength{\hoffset}{-10mm}
\setlength{\oddsidemargin}{-8mm}
\setlength{\evensidemargin}{-8mm}
\addtolength{\textwidth}{16mm}

%%%%%%%%%%%%%%%%%%%%

\renewenvironment{itemize}{
  \ifnum \@itemdepth >\thr@@\@toodeep\else
    \advance\@itemdepth\@ne
    \edef\@itemitem{labelitem\romannumeral\the\@itemdepth}
    \list{
      \csname \@itemitem\endcsname
    }{
      \def\makelabel##1{\hss\llap{##1}}
      \setlength{\leftmargin}{\defaultleftmargin}
      \setlength{\rightmargin}{\defaultrightmargin}
      \setlength{\topsep}{\defaulttopsep}
    }
  \fi
}{
  \endlist
}

\renewenvironment{enumerate}{
  \ifnum \@enumdepth >\thr@@\@toodeep\else
    \advance\@enumdepth\@ne
    \edef\@enumctr{enum\romannumeral\the\@enumdepth}
    \list{
      \csname label\@enumctr\endcsname
    }{
      \usecounter{\@enumctr}
      \def\makelabel##1{\hss\llap{##1}}
      \setlength{\leftmargin}{\defaultleftmargin}
      \setlength{\rightmargin}{\defaultrightmargin}
      \setlength{\topsep}{\defaulttopsep}
    }
  \fi
}{
  \endlist
}

%%%%%%%%%%%%%%%%%%%%