Compromised diagonal and dropping back
This sort of pattern on the side is quite common after an invasion:
To play at a is clearly slower and heavier, even though it has more effect on Black too.
Here is a very special case of this shape.
This choice of (instead of Black at a, in the 3-5 point low approach one-space low pincer) is an example of a play that is recorded in joseki dictionaries, but rarely seen in pro games.
From what is said at weak player's diagonal, one can understand the rarity: Black at a is very natural from the point of view of shape. Of course can be called a lighter play.
Presumably is intended as a sort of inducing move. Black wastes no time playing at another key point of White's diagonal.
Kajiwara was nicknamed 'the drill' for his maximum attitude to local play: is a good example. A ko results.
Here (dropping back with a diagonal play) shuts White in, rather than chase him out into the centre.
By (move 120) this is the endgame. Black won by resignation, at move 213.
 The opening plays were these: