Just when he has made a complete mess with the relationship with China over the Senkaku Islands, and when a questionable accounting of Tokyo's failed Olympic bid for 2016 starts to surface, he calls it quits.
From Asahi Shinbun tweet (10/25/2012):
Governor of Tokyo Ishihara held an emergency press conference and announced that he would resign as the governor. "I resign as the governor as of today. I intend to return to the National Diet. I will form a new party with the like-minded people", he said. The press conference is still ongoing.
Ishihara is probably quite popular with people whose source of information is the traditional media (TV, newspapers, magazines).
The boy-wonder mayor of Osaka City, who is badly trailing in the polls but continues to be a media darling (good or bad), was in talks with 80-year-old Ishihara at one time about possible cooperation.