If the demographics swing at the edges of the market the center will respond. Particularly if there is social pressure to do so. This is not a malicious endeavor it is a market response and we frankly don't have to be so hand-wringy about it.
All sexual material sold legally in Japan is censored by law.
Many people in this thread are talking about how 'the market should adapt' or 'the market doesn't need to adapt', but I think a more interesting corraly is that 'the market' is the primary force acting on the culture of this niche. Japan is lucky to have a diverse comic market, but I think there's an interesting case to be made for non-market forces to encourage a broader set of creativity in the comic world, if not for the young girls at the very least countering the incessant duldrum I find myself stepped in as a consumer.
I'm not versed enough in the law to answer the spirit of that question, but the law has chilling effects greater than the letter of it. Adult material is kept in a separate section, usually with the books sealed in opaque packaging, and 7-eleven in Japan has removed it's adult section entirely.
