Harenchi Gakuen

is a Japanese media franchise created by Go Nagai. Harenchi Gakuen was one of the manga serialized in the very first issue of Shueisha's manga magazine Weekly Shonen Jump. The series was the first big success for Go Nagai. It is also considered as the first modern erotic manga, sometimes considered the first hentai manga, though Nagai never used explicit sexual situations in the original run of the manga.