This is a beautifully shot movie and is definitely not a cheaply made porn. It's made to stand up as a legitimate movie and entertainment for adults.
Maya Takigawa (Yumi Takigawa) is enjoying her last day of freedom, having a wild time, because tomorrow, she will be entering a convent. She meets a good looking guy Kenta Aoki (Hayato Tani) and becomes friends with him. He wants to go steady with her but she declines. What's driving her to enter the convent ? 18 years ago her mother was at this convent and committed suicide while being pregnant with her. She aborts early but survives. She's now on a mission to find out why her mother had to die and who is her father. After she enters the convent, it's nonstop erotic violence with nuns beating up each other in name of God with beautiful breastages, and naked bodies shown at every opportunity.
The movie is high quality as it has real story, beautiful "real" actresses who can actually act, and crisp cinematography that's top notch.
How did such far out, and excellent movie come out from a rather conservative Toho studio ? I can put all the credit squarely on the director Norifumi Suzuki's capable talent. Suzuki is not well known in the west because he himself prefers not to be in the front line, but he is an unmistakable genius of Japanese cinema, and have directed many famous (and some considered masterpieces) of movies and movie series such as "Torrakku Yaro" (Trucker Guy) series starring Bunta Sugawara and "Hibotan Bakuto" (Hibotan Gambler) series starring Junko Fuji. Sugawara and Fuji both became famous after starring in Suzuki's movies. Suzuki's movies are all known to be somewhat eccentric and squarely focused on entertainment value. He is very versatile as he can direct movies of many different genre all with very high quality.
Seijyu Gakuen (Holy Beast School) gets all it's quality and entertainment values from the talent of its director. Beautiful Yumi Takigawa makes her debut in this movie, and she enjoys a long career as a movie and TV actress in the proceeding years.