"Via Google translate: 'The thorn crotch (it points and) [ the crime prevention supplies ]'"
Reader comment: William Van Hecke says: "The 'thorn crotch' is actually called a 'sasumata,' and dates back to the Edo period. The idea is not so much to carry it around with you, but to have it on hand in case someone threatens your home or place of business. Think of it as a less aggressive version of the baseball bat (or shotgun) some of us westerners keep around. Link
Reader comment: Justin says: The so-called Thorn Crotch is actually a tool present in all elementary schools and (as far as I know) many if not all junior high schools in Japan. There are regular teacher and student training exercises that we've roughly translated as "the scary man drill." A scary man with a fake knife runs in to a given classroom, students shriek and run for cover, and a designated student runs to get a teacher with the scary man device. Then they chase each other around until the scary man gets pinned against a wall.
Reader comment: Kyle Goetz says: In case any readers are interested, I translated the Sasumata ad you posted on Boing Boing. Link