The Kitani move
Go Seigen has this to say about : B doesn't want to play a so that W would play at
to form the "avalanche shape", so
move applies the proverb "opponent's key point is also my key point."
Note that White does not necessarily play at a immediately.
White may also play sagari instead. However, this is probably only good if white already has some stones along the top side. In a game where Kitani played this against Go Seigen, Go had the following to say about this variation: The sequence to here would be certain. Not only would Black have a peep at a (followed by a response at b ) and then an extension to c , and
are also unsatisfactory.
(Though I suspect that many things unsatisfactory to Go Seigen might still be quite acceptable in an amateur game...)