Why hasn't Japan banned child-porn comics?

http://www.bbc.com/news/magazine-30698640
Why hasn't Japan banned child-porn comics?
"Everyone knows that child abuse is not a good thing," Hide says. "But having that kind of emotion is free, enjoying imagining some sexual situation with a child is not prohibited."
His candour takes me by surprise. He then introduces me to the word "Lolicon", short for "Lolita complex" - the name for manga featuring young girls engaged in sexually explicit scenarios. It can involve incest, rape and other taboos, though Hide's tastes lie more with high-school romance.
"I like young-girl sexual creations, Lolicon is just one hobby of my many hobbies," he says.
I ask what his wife, standing nearby, thinks of his "hobby".
"She probably thinks no problem," he replies. "Because she loves young boys sexually interacting with each other."
...
Among the manga shops of Akihabara, child protection campaigner Kazuna Kanajiri takes me to see something she thinks is a much bigger problem than cartoons and comics. We climb a flight of stairs off the main street and emerge into a room packed full of DVDs.
Kazuna picks one off the shelf - it features real images of a girl she says is five years old, wearing a skimpy swimsuit and posing in sexually suggestive positions that mimic adult pornography. All the other DVDs in the shop also feature real children.