The numbers involved are huge: hundreds of thousands of movies, along with millions of dollars changed hands over the five years that this ring was active, according to Japanese authorities.
The leader of the ring was 53-year-old Takahiro Oyama, who said that he made 1.56 billion yen ($14.4 million) by selling the illegal sex tapes over the Internet and through the mail.
Child pornography occupies a unique place in Japanese law. It's legal to own the material for personal use, but since 1999, it's been illegal to produce or sell it.
Oyama and his 10 underlings were arrested for the attempted distribution of about 133,000 child porn DVDs and videocassettes.
Police said that their investigation into Oyama's child porn ring will include a probe to see if he worked with any gangs.