Is Bit Torrent illegal in Japan?

I recently received a cease and desist warning from the school that I am studying at for "use of illegal file sharing software", which I can only assume means Bit Torrent. I was using it to torrent some movies from vo.do, which is a site that hosts bit torrents for movies which have a specific licensing agreement which makes them legal to torrent. Is use of bit torrenting software illegal in Japan, or is my school just jumping the gun and assuming that I'm using it for illegitimate purposes?