He is a manga-ka who writes mens' hentai/ecchi manga and is also very popular with his target audience. Seiji Yamada, the protagonist of Sensitive Pornograph, is quite shocked to find out Hanasaki-sensei is a man, since most of his fans (and fellow manga artists) think he's a girl, mostly due to his feminine looks and personality. Seiji is a huge fan of Sono Hanasaki's manga, adoring the cute girls and beautiful displays of eroticism in his work. He is also a fan of Seiji Yamada's work and eventually the two become lovers... instead of just work-mates.

Sono Hanasaki is actually 32 years old, even though he doesn't look like it.