Every aging society faces distinct challenges. But Japan, with the world’s oldest population (27.3 percent of its citizens are 65 or older, almost twice the share in the U.S.), has been dealing with one it didn’t foresee: senior crime. Complaints and arrests involving elderly people, and women in particular, are taking place at rates above those of any other demographic group. Almost 1 in 5 women in Japanese prisons is a senior. Their crimes are usually minor—9 in 10 senior women who’ve been convicted were found guilty of shoplifting.