Choshi Public High School is called as "Oyama" (meaning mountain) by the locals. It is considered to be the model for Kibito High School, which the characters in Amagami attend. There are various modeled locations both inside and outside of the school. For example, corridors, rooftops, and school routes.
*Please don't enter this school for the purpose of filming or anything else. You can only enter the school when it's open to the public, such as during the school festival.