The bisentō (眉尖刀) is a long spear with a curved steel tip used in feudal Japan.
Much heavier in structure than the naginata, it is primarily used as a training weapon to improve one's Naginata-do, the art of the halberd.
The history of this weapon is rather obscure, and there are various descriptions of it: "a long double-edged sword with a thick blunted blade," "a weapon similar to a spear with a scimitar-like end," "a polearm resembling a halberd with a long and heavy curved blade."
The Kukishinden Ryu claim that the weapon was introduced from China during the 5th century, which would make the bisentō the most likely precursor to the naginata. Used in warfare as a weapon against mounted warriors, it would have been employed against both the horse and the rider.