Bittorrent

University of Buffalo student Bram Cohen released the first version of Bittorrent in 2001. Initially, Bittorrent had relatively little impact on the Japanese p2p scene, as first WinMX and then Winny and then Perfect Dark seemed to get the most use. Eventually though, western and Chinese developers released Japanese versions of their clients: Bittorrent, Bitcomet, qbittorrent, Deluge and Transmission. Qbittorrent has no ads, is lightweight, and is perhaps the best-regarded of the current crop of torrenting programs on the English web.

While programs like Perfect Dark try to provide anonymity, the IP address of a user is clearly visible in most torrent programs, so some users turn to anonymizing addons (e.g. i2p, Tor), clients (Tribler), proxies (Cybersyndrome), seedboxes (Seedr) or virtual private networks (Hide.me) in an effort to preserve their privacy.

The number of Japanese users on Bittorrent may be smaller than other networks, but by 2013, the bandwidth being used in Japan by torrent clients had apparently surpassed all other p2p networks.

I don't think there are any torrent trackers based in Japan, but there are quite a few trackers and index sites in the rest of the world that link to Japanese content.

- Nyaa is the largest Japanese tracker, and focuses on anime and music. It does have some manga and live action tv shows, often with an anime tie-in. Nyaa has an associated site for adult videos at Sukebei.

- Tokyo Toshokan　東京図書館 is a torrent index of adult videos, anime, games, hentai, manga, music and TV dramas. The torrents are often tracked on Nyaa or Sukebei or the other trackers listed here.

- Akiba Online is an English Language forum with a huge number of Japanese Adult Video downloads hosted on Filejoker, but it has a sizeable torrent section covering JAV, Idol and Hentai as well as more mainstream manga and anime.

- Rutracker is a tracker/forum completely in Russian, but it has a surprising amount of Japanese movies, books and CDs, often labelled in Japanese.

- Avistaz is a private tracker with Japanese, Chinese and Korean movie and TV drama torrents.

- Bt4g appears to be a Chinese torrent search engine compiled by scraping Distributed Hash Tables, and thus has torrents with Japanese content. BTDig, Solidtorrents and Bitsearch are western DHT torrent search engines. Torrentkitty is a Chinese/Singaporean torrent search engine with a Japanese interface. - Javbus, Onejav and Javjunkies are blogs where the webmaster posts torrents for Japanese adult videos. - The Download board on 2channel is one of the main forums for discussion of Japanese file sharing. At the moment, there are several Bittorrent related threads. The BTで拾えるエロ動画スレ thread deals with erotic videos that can be picked up on Bittorrent. The Nyaa thread is devoted to a discussion of torrents that can be found on the Nyaa tracker/index site. The BitTorrent総合スレ thread covers general Bittorrent matters. There are also now threads on Akiba Online and Javjunkies.

- Nipponsei Music Fresh from Japan is a torrent tracker/index of music, mainly anime soundtracks and J-pop.

- Jpopsuki is an invitation-only private torrent tracker for J-pop.

- Anime Sharing is a forum focused on links to direct downloads for hentai manga, but it also has a torrent section with hentai anime and games, and there is a smattering of music and magazines.

- Anirena is an English anime torrent tracker/database.

- D-Addicts was at one time a tracker for Japanese, Chinese and Korean dramas, but now it is just a forum where torrents are not allowed to be posted. it has some subtitles though, and lots of information about file sharing in Asia.