Maai
Maai (間合い?), translating simply to "interval", is a Japanese martial arts term referring to the space between two opponents in combat; formally, the "engagement distance". It is a complex concept, incorporating not just the distance between opponents, but also the time it will take to cross the distance, angle and rhythm of attack. It is specifically the exact position from which one opponent can strike the other, after factoring in the above elements. For example, a faster opponent's maai is farther away than a slower opponent. It is ideal for one opponent to maintain maai while preventing the other from doing so, meaning that they can strike before the opponent can (rather than both striking simultaneously, or being struck without being able to strike back).
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