Japan’s revised copyright law was partially enforced  on October 1, 2012, and now penalizes the act of illegal downloading and DVD ripping for personal use. If arrested, one will be sentenced for up to 2 years in jail or fined 2 million JPY, which is approximately US$ 25,680.
Internet users have shown concern in reaction to the new law. Movements for the Internet Active Users made a statement  [ja] against the bill on June 6 when it was drafted.
- Youth with little opportunity to understand the law will be the most affected
- The definition of legal and illegal is vague and hard to judge
- It could lead to abuse of [police] investigation power
- It needs a well-deliberated discussion
The shift to penalties caused confusion and fear among Internet users. One comment on Twitter  describes how information transformed into misinformation:
Here's how information transformed. “Penalty for illegal download starts October 1st” –> “Crackdown on Copyright infringed websites” –> ” derivative works are copyright infringement?” –> ” ban on derivative works starts October 1st” –> “Sign the petition! 100,000 signatures are needed or niconico movie, pixiv websites and independent distributions will have to shut down!” Look how inaccurate (the information) became by the end.
Some Twitter users sent warnings about the misinformation. User @fu_ryukei  cautioned:
【拡散希望】「二次創作禁止令の法律が10月１日からに決まった」というツイートが拡散されていますが、正しくは「違法ダウンロード刑事罰化が10月１日から」です。 二 次 創 作 そ の も の を 禁 じ る も の で は あ り ま せ ん
I saw some tweets going around saying “The law bans derivative work from October 1″ but that's incorrect. The penalty of illegal downloads starts from October 1. It is not about a ban on derivative works.
Another user  also warned:
「二次創作禁止令」という法律は存在しない。ただのデマ。 ただし、無許諾の二次創作は著作権法違反。親告罪なので、原作者からの黙認・削除依頼・告訴…といった形で折り合ってきた。 10/1違法DL刑罰化施行からは、音楽・動画の無許諾二次創作に限り、ダウンロードも刑罰対象(親告罪)。
There is no such thing as “No-Derivative Work Act”. It's a false rumor. However, derivative work without permission from the author is a copyright infringement. It is an offense subject to prosecution only upon complaint, so if the author overlooks it or asks to take it down, then a court appeal may result. After October 1, if you download derivative work made without permission of the author, it is subject to penalty upon complaint.
On July 24, the Japanese Agency for Cultural Affairs published frequently asked question s [ja] about the law, but it is unlikely that these details will bring an all-inclusive definition and understanding towards copyright issues. The government's site run by their Public Relations office also published details of the new copyright law. On their page  [ja], they describe that the intention of the law is to prevent piracy from damaging the profit of rights holders, such as the revenue from paid-distribution, sale of CDs and DVDs.
One Twitter user  looked back to the discussion on penalizing illegal downloads after discovering that Japan ranks number one in spending on CD per customer; spending the largest amount of money in the world:
つまり、ダウンロード刑事罰化の議論とはいったいなんだったのか、と。 .@biac_ac さんの「TV「世界番付」を見て、「CDを買う国」ランキングの1位が日本だと知った人の反応」をお気に入りにしました。 togetter.com/li/361017 
So what was the purpose of introducing penalty for illegal download in the first place? .@biac_ac Here's a link curating the reaction of Twitter users who found Japan is the biggest CD consumed country in the world, according to a television program. togetter.com/li/361017 
Thumbnail image by HikingArtist.com  CC BY NC-ND 2.0