To cite package ‘jpops’ in publications use:

  Uryu S (2024). _jpops: Provides a Data Set on the Population in
  Japan_. R package version 0.0.0.9000,
  <https://github.com/uribo/jpops>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {jpops: Provides a Data Set on the Population in Japan},
    author = {Shinya Uryu},
    year = {2024},
    note = {R package version 0.0.0.9000},
    url = {https://github.com/uribo/jpops},
  }