FutaOna: Toaru Futanari Musume no Onanie Nikki

This particular doujin follows the story of a certain futanari girl named Tomoe Hanagasa as she paints the town with cum, so to speak. Ever since she learned how to masturbate, she became more and more perverted falling down a downward spiral of sexual thrills and debauchery. Eventually, reaching a point of no return...