\documentclass[
  year = 2018,
  language = japanese,
  translationsInputFile = frog-japanese.tex,
  imageFolder = ./photos/,
]{wallcalendar}

\usepackage{local-japanese}

% Content is the same across translations
\input{./frog.tex}

\begin{document}

% Just one month
\MonthPage[layout=full page, put photo=full page]{September}

\end{document}