\documentclass{Book_Class}[2020/05/12]
\begin{document}
\newgeometry{textwidth=\paperwidth-12mm-12mm,textheight=\paperheight-15mm-7mm-8mm}
\setlength{\hoffset}{0mm}
\setlength{\evensidemargin}{12mm-1in}
\setlength{\oddsidemargin}{12mm-1in}
\setlength{\marginparsep}{5mm}
\setlength{\marginparwidth}{0mm}
\setlength{\voffset}{0mm}
\setlength{\topmargin}{15mm-12pt-5mm-1in}
\setlength{\headheight}{12pt}
\setlength{\headsep}{5mm}
\setlength{\footskip}{7mm}
\tableofcontents
\newpage
\setcounter{page}{1}
\restoregeometry
\input{./Chapter_1}
\input{./Chapter_2}
\input{./Chapter_3}
\input{./Chapter_4}
\input{./Chapter_5}
\end{document}