Mobile Detective "Takako" sends out a message “Search the N on Internet” through various media. Users who have visited the site get involved with solving a theft case of “drop of N (902 carat diamond)", making full use of “FOMA N902i”, with an onboard shake proof camera, to find and collect evidence in rooms of six suspects. When users finish collecting all evidences from every suspect’s room, they can finally find out who the true criminal is. Only users who could reach to the truth of this case can apply for the prize.