Japan had rather lax copyright laws but it seems that recent studies on just how much pirating and illegal uploads are costing the manga industry has led to some radical changes. Under the new laws proposed by Japan's Agency for Cultural Affairs, posting anime images, illustrations, photos on personal blogs or social media would be deemed illegal, as would posting song lyrics (that last one is a head-scratcher).
In addition, even if you're not the person uploading the material and simply took a screenshot of the offending material, you would still be punishable under the new law.
In this era of YouTube and social media personalities, such a law seems quite oppressive. Per ANN, the Japan Cartoonist Association has weighed in on the matter, issuing the following statement, "We ask that due deliberation is taken to ensure that the expansion [of copyright law] does not impede civil rights such as research and freedom of expression."
Specifically, the association wants the law to target repeat offenders, individuals who upload original art without alteration and instances where a property's profit margins are directly affected.
How this new law would affect doujinshi or commissioned art is also a bit of a gray area. Stay tuned to Anime Mojo for future updates.