Wikipedia contains an informative article on the object of your inquiry.
The entry includes the history, social setting, business purpose, and
legal ramifications [in Japan] of the things called "junior idol."
See the Wikipedia article here: http://en.wikipedia.org/wiki/Junior_idol
In Japan, where the photos and videos are made, the law prohibits any
depiction "in a way that can be recognized visually, such a pose of a child relating to sexual intercourse or an act similar to sexual intercourse with or by the child", of "a pose of a child relating to the act of touching genital organs, etc." or the depiction of "a pose of a child who is naked totally or partially in order to arouse or stimulate the viewer's sexual desire."
Apparently, some of the depictions [photos or videos] of junior idols cross the line into "pornography." The article notes one filmmaker's prosecution under Japan's law for "the prolonged filming of [a17 year old] girl's genitalia."
All this, has to do the the law in Japan. Not he U.S.
In general, the law in the U.S. has defined "pornography," as any image which stimulates the viewer's prurient interest." As stated, this formulation seems to suggest that "pornography" only exists in the mind of the beholder. Like one famous Supreme Court Justice said, "I know it [pornography] when I see it."
In the United States, child pornography is prohibited under 18 U.S.C. Chapter 110, Sexual Exploitation and Other Abuse of Children. While this law defines child pornography as “depictions of a minor engaging in sexually explicit conduct,” the actual definition of what is a pornographic image is somewhat more subjective. Many court cases now use “Dost factors” (named after the U.S. v. Dost case in 1986) to determine whether an image is pornographic: these factors ask whether the focal point of the visual depiction is the child’s genital region; whether the setting of the image is sexually suggestive; whether the child is posed unnaturally or in inappropriate attire; whether the child is nude, semi-clothed or fully clothed; whether the picture indicates the child’s willingness to engage in sexual activity; and whether the image is intended to elicit a sexual response in its consumer or viewer. Notwithstanding the popularity of these factors, the U.S. Supreme Court has also stated that fully clothed images may constitute child pornography.
This federal law targets those who actually hire the child, make the images, and distribute or sell the images, or possess the images.
Your real question is whether viewing such images on internet websites constitutes "possession." I would think not, but I would not want to be the one to test that particular case. And, you don't either. But, downloading and storing an image of the type covered by 18 U.S.C. 110, I am sure can get you into bad trouble:
"Consumption of child pornography can lead to a maximum penalty of five years in federal prison, while distribution of child pornography has a maximum penalty of 15 years in federal prison."
Because merely viewing child pornography may, by some people, be considered "consumption," if I were you, I'd find something different to look at. You're on the edge of a precipice here. Is it worth 5 years in prison if you should fall?
BTW---"Anime," because it is a cartoon, and not a real live person being depicted, should be beyond the reach of the law quoted above. Even so, I wouldn't want to push that issue either.
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I don't actually know the answer to your question, but Mr. Fahey's summary sounds very good to me. The vigilantes that concern themselves with this type of images are not known for subtlety, sophistication, empathy, or mercy. Remember that "deleting" something on a computer doesn't erase anything, it merely repositions it on the hard drive and removes the directions about how to find it. It's still there, somewhere, and a knowledgeable searcher will find it. Messing with porn on the internet is very risky, because someone may send you something illegal, that they have misrepresented and you did not ask for. But there it is, on your computer. And a repairman is obligated to report it to the police if he comes across it.
As Mr. Fahey says, find something else to look at.
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