R language is becoming a robust geocomputation tool as it provides reproducibility. A new R package geojp has been developed to use various geographical data of Japan, including National Land Number Information data provided by Ministry of Land, Infrastructure and Transport. This paper introduces the new package which allows to download the data and read as an sf object. The paper also demonstrates spatial join features, which are incorporated in R/sf but have not been well explained. This paper introduces how to use Japanese geographical data with the new R package, and demonstrates spatial join with a case study of locational analysis of facilities, followed by statistical analyses.