Maai is the distance between you and your opponent. .Those that control the distance control the encounter. The goal is to put your opponent in a weakened position while you maintain a position of strength. In Wado Ryu this is a vital aspect. We use deflection, evasion, body shifting and entering techniques to achieve this. Being in harmony with our opponent we can use their force against them, to defeat or frustrate them. If your opponent goes up, we go down, if the move left, we move right, when they attack directly, we move in circles, when they attack in circular action, we use angles to enter directly.
Maai does not only refer to your opponent but also your surroundings. Be in harmony with your surrounding, force your opponent into obstacles or uneven ground, have the sun behind you etc. Maai refers to the harmony of your surroundings when not in conflict, this needs to be studied to understand. But a simple example is, there is no bad weather, just inappropriate clothing.