A years-long investigation just unmasked a major torrent pirate, the how remains unclear

In a multi-year investigation, the Kyoto Prefectural Police have apprehended Masakazu Ono, a 56-year-old resident of Sagamihara in Kanagawa Prefecture, on charges of uploading copyrighted TV programs to the torrent site Nyaa. The case has garnered attention due to the unconventional investigative methods employed. Instead of monitoring BitTorrent swarms, investigators from the anti-piracy organization CODA examined how data flows between torrent index sites and trackers.

Ono is alleged to have been the first person to make complete files available for download, a role known as an initial seeder. The investigation, initiated by CODA in 2021 as part of its Cross-Border Enforcement Project, involved collaboration with the Japan Hacker Association (JHA) before the involvement of Kyoto police in 2024.

During the probe, nearly 1,000 NHK recordings were allegedly uploaded by Ono. Three secondary uploaders associated with the case have been charged since 2025, though the specifics of how Ono was identified remain undisclosed. CODA's approach involved analyzing how information moves within torrent sites, leaving open the possibility that investigators monitored newly posted torrents over time to trace the source of files.

Additionally, the involvement of JHA, known for decrypting peer-to-peer protocols, may have contributed to identifying Ono's activities. While the precise method of identification is not publicly disclosed, it is possible that factors such as the use of a non-VPN connection, website cookies, or content-delivery-network logs played a role in connecting Ono's actions to the alleged copyright infringement.

Japanese law imposes restrictions on broad internet monitoring, limiting the use of techniques like deep packet inspection or large-scale traffic-volume monitoring before a suspect is identified.