Yari is Japanese word for spear, and just like spears across the globe, they have been made in many forms.
The 'trident' Yari was somewhat unique, in that it had 2 sideways blades sweeping upward to either side, capable of cutting in any direction.
Some more advanced examples also incorporated an additional crossguard approximately 1 third down the shaft.
1.85m Trident Yari