To cite package ‘japanstat’ in publications use:

  Uchida M (2021). _japanstat: Tools for Easy Use of 'e-Stat' API_. R
  package version 0.1.0,
  <https://CRAN.R-project.org/package=japanstat>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {japanstat: Tools for Easy Use of 'e-Stat' API},
    author = {Mizuki Uchida},
    year = {2021},
    note = {R package version 0.1.0},
    url = {https://CRAN.R-project.org/package=japanstat},
  }