User blog comment:IamJakuhoRaikoben/Chapter 462: Battlefield, Review./@comment-86.66.207.37-20151116154533/@comment-76.161.172.226-20151116171230

Four people actually.

http://www.animenewsnetwork.com/news/2015-11-13/3-men-arrested-for-uploading-one-piece-chapter-to-english-website/.95349

Only One Piece is mentioned but odds are good that was their raw provider for all their Jump series, and possibly their WS Magazine series as well. If they weren't their WSM provider, odds are good they're keeping a lower profile anyways as a result.

Worst case scenario, that might have even have been MP's scanlation team.