To cite package ‘jcalendaR’ in publications use:

  Kobayashi M (2024). _jcalendaR: Interconversion Between the Japanese
  Calendar System and the Western Calendar_. R package version
  0.1.0.9000, <https://github.com/indenkun/jcalendar>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {jcalendaR: Interconversion Between the Japanese Calendar System and the
Western Calendar},
    author = {Mao Kobayashi},
    year = {2024},
    note = {R package version 0.1.0.9000},
    url = {https://github.com/indenkun/jcalendar},
  }