Gyaku sankaku

Gyaku sankaku is the judo name for the reverse triangle — the inverted-orientation triangle caught with the opponent turned away or the attacker inverted relative to them.

Etymology. Gyaku (逆) means “reverse” or “inverted”; sankaku (三角) means “triangle.” In the five-triangle classification the reverse triangle is defined by orientation: the attacker faces the opposite direction to a front triangle, with the outside leg over the opponent’s shoulder and the inside leg tucked underneath. The naming overlaps untidily in older literature — “gyaku” and “ushiro” are sometimes heard for each other’s techniques — but the five-way classification settled modern usage.

Mechanics. The figure-four closes around head and one arm from the inverted orientation; the strangle works by forcing the opponent’s own trapped shoulder into their neck. It appears from underneath pins and in scrambles as a surprise counter, and it feeds armlock follow-ups when the strangle stalls.

Cross-reference. English-speaking no-gi uses “reverse triangle.” Full mechanical coverage on Reverse Triangle.