Move 7

B #7 is Kitani 9 dan's unique move; other players rarely play it, but Kitani 9 dan has used it a few times in openings like the 1-3-5 of this game. B doesn't want to play B[a] so that W would play [7] to form the avalanche shape”, so the [7] move applies the proverb, the opponent's key point is also my key point.”