The novel that this movie based on is a true story about the author himself Nobutaka Tsubota, who runs a private institute, and his student Sayaka Kobayashi.
Based on the novel "Gakunen Biri no Gyaru ga 1 nen de Hensachi o 40 Agete Keio Daigaku ni Geneki Gokaku Shita Hanashi" by Nobutaka Tsubota that was published in December 26, 2013 by Kadokawa.
Japanese title Biri Gyaru or Biri Girl in English means girl who wears miniskirts and dyes their hair blonde. It was the name for the outfit trend that starts by popular Japanese singer Namie Amuro in 90s.