From iA wiki
Winny is a peer to peer file sharing application that is not well known outside Japan. Winny provides distributed bulletin boards and claims to provide anonymised file transfers. Files are reportedly relayed through other users instead of being transferred directly from the node storing the file to the node downloading the file, although details are lacking.
The client and all the information on the web about winny is in Japanese. The developers of winny do not want it to be use outside Japan. A small number of people outside Japan use winny to get Japanese content such as anime. The Japanese take a permissive attitude to pornography.
A few users of winny were arrested in 2003, reportedly because the IP Address of the node that creates a new bulletin board can be determined and these users had written incriminating messages when creating new boards.
Isamu Kaneko, creator of winny used the codename "47-shi", pronounced is "yon-jyu-nana-shi". It means "Mr. 47" in Japanese. On the 31 May 2004 he was charged with assisting the distribution of copyright material by the Kyoto District Public Prosecutors' Office.
There is also a program called Share which is based on winny but operates as a seperate network.
- Free Isamu Kaneko, defense fund for winny developer