At the very least, for the time being there is going to be a chilling effect on anime and manga creators. They will constantly have to stop and assess their works against the law, or what the lawyers in the company interpret the law to be. Publishers will be forced to become more conservative with their stories, potentially sidestepping any criticism or commentary on major social issues.

As Simon Jones of Icarus Publishing pointed out in a blog post in June celebrating the defeat of the “Nonexistent Youth Bill” (possibly NSFW content), the anime and manga industries are “predominantly female” and any legislation restricting creativity in these industries would have a disproportionate effect on the female workforce. I think this is even more of a concern with Bill 156. I don't think the majority of shounen series will experience much fallout from the bill. However, an emphasis on sex and relationships is more frequently seen in shoujo, josei, and yaoi manga, where both the creators and consumers are largely female. Although it seems gender-neutral on the surface, it could be women who feel the brunt of the enforcement of Bill 156.

Many Japanese publishers are against this bill for many of the same reasons they were against the first “nonexistent youths” bill – it unevenly restricts freedom of speech and is so vaguely worded that they are unsure if the manga or anime they are putting out would be in violation.

The bill also doesn't mention doujinshi and other works created by fans. Of course, a lot of doujinshi with sexual content are already for adults only, so it would have little effect even if the law applied to such fan creations. Also, the main punishment for breaking the law is removal of access to distribution and retail, which wouldn't really impact artists who may make more of their sales directly to fans at Comiket.

the bill has nothing to say about any manga or anime that's currently considered adult. All of those titles that are currently for sale only to people over the age of eighteen won't be directly impacted by this. I've seen a number of people saying that they might be in favor of this bill because it would get rid of some of the horribly violent manga that feature sex with underage characters. However, this bill has absolutely nothing to say to anime or manga like that – they would still be able to be sold to adult consumers.

The bill puts an emphasis on self-regulation, with the expectation that publishers will begin policing themselves. (However, this may be hard to do since the bill is still vaguely worded.) If a publisher runs afoul of the bill too many times, then they may face what is in essence a blacklist, with no distributors or retailers able to carry their products.

The bill goes into effect in April 2011, and it's presumed that materials that were published before this date won't be affected. However, new editions of previously published anime and manga will presumably fall under this law.

Since Dan Kanemitsu has been writing frequently about this bill, I'll just quote his summary of the relevant portion of it, which will restrict “any manga, anime and video games that feature any sexual acts that would violate criminal codes or Tokyo ordinances OR sexual depictions between close relatives who could not legally get married to be treated as adult material IF they are presented in [an] ‘unjustifiably glorified or exaggerated manner.’” In some ways the language of the bill clarifies things, since we no longer have to try to figure out if a character meets the qualifications of being a “youth” in order for the restrictions in the bill to apply. However, by taking out the language regarding youth, it actually means that Bill 156 could have a potentially wider reach than the one that was defeated earlier in the year. Additionally, the part about presenting such scenes in an “unjustifiably glorified or exaggerated manner” is open to a wide variety of interpretations.