However, if you aren't already breaking copyright law in Japan, then you should be okay—even if you are checking out illegal content on YouTube.
The new law, which was passed by legislators this summer, is a stricter revision of the country's copyright law. As of today, downloading illegally uploaded materials is punishable by up to two years in prison and approximately US$25,000 in fines.
When the law was originally announced, Japanese tech pundits worried that the law could kill YouTube, a site rife with illegally uploaded movies and TV shows.
Japan's Agency for Cultural Affairs has explained the nitty-gritty of the law, going into detail about some of the finer people net users in Japan have been worried about.
In short, if you check out illegally uploaded files on YouTube, that is not illegal (having it on your cache for playback doesn't count as downloading, it seems). However, if you actually download said files onto your computer, then that would be illegal. Thus, YouTube will continue, business as usual, for the vast majority of users in Japan.
Another interesting exception is that it is not a crime to download an illegal file as an email attachment—as, I guess, the logic is that the email recipient might not know what he or she is downloading. Fair enough.
Yet, uneasiness persists online in Japan as net users anxiously wait to see how this law is enforced and how to navigate the gray area between what's allowed and what no longer is.