shikomizue
The shikomizue, shikomi-zue (仕込み杖, "prepared cane") or jotou (杖刀, "staff sword") is a Japanese sword stick or concealed weapon.
It is most famous for its use by the fictional swordmaster Zatoichi. The sword blade was placed in a cane-like mounting (tsue) as concealment.
Some shikomi-zue also concealed metsubushi, chains, hooks, and many other things. Shikomi-zue could be carried in public without arousing suspicion, making them perfect tools for ninja.