Kamayari
The kamayari (鎌槍, sickle spear) is similar to the jumonji yari. While it also had two protrusions shooting off the base of a main spear tip, in yari the offshoots were hooked back downward. The kamayari essentially is a yari with kama at the base of the blade to assist in hooking things. Generally the hooks are large enough to hold the head, neck or jaw (when in a tree) or to hook limbs of a swordsman on the ground, thus it is different in function in this respect from other types of yari. Also the kamayari was used to hook horsemen and dismount them.[1]
Historically it also had a non-military use, where it was employed by Japanese firemen to pull down the roofs of burning buildings to slow a fire much the same way firemen of today would topple buildings to create a firebreak.
There is also a single hooked variety of the kamayari called the katakamayari.