The godmother of manga sex in Japan:
"A recent UN report weighed into a debate that provokes intense
controversy in Japan, by including manga in a list of content with violent
pornography. The BBC's Yuko Kato went to meet one of Japan's leading
female manga artists, Keiko Takemiya, seen as the woman who opened
the floodgates to sexually explicit manga.
Some readers may find some of the sexual details that follow disturbing."
See:
http://www.bbc.com/news/world-asia-35714067