Karumai College served as a model for the Shinzen High School in the Saitama area. The only college in the city. One can also guess that this is the college that the author studied. By observing the Karumai municipal gymnasium, the staircase is identical. Paragraph 91 of chapter 85 "Zasshoku" of volume 10 of the manga. The site of the school is forbidden to any outside person.