Police arrested Sho Okuma, 26, unemployed, who lives in Soka, Saitama Prefecture, on 2 August, and Nao Sato, a graduate student at the Tokyo University of Agriculture and Technology, who resides in Koganei, Tokyo, on 3 August, the sources said. The two are accused of conspiring to send a fax to the Tokyo College of Music on 23 January, demanding, "Pay 300,000 JPY (USD 2,060) or the bomb we set will be detonated." The threat was conveyed through a service that allows mass fax sending via the internet. The two men accessed the service through Tor, a system that allows faxes to be sent anonymously. It is rare for a criminal case involving the use of Tor to be filed.