Joseki Opening (3-4) Episode4

Primary Sequence 2  

Black 1 was played often before Primary  sequence 1came out . Because Kitani Minoru favored this particular sequence. it is called the Kitani Jungsuk White's approach'and'extension at 4 is too important to neglect because , after Black approaches at 1 as shown in Diagram1, it becomes almost impossible for White to invade  Black's territory on the left side . Black can therefore use Primary Sequence 2 to take sunsoo by use leaving his territory unprotected after white 4,but inthat case , he will face a difficult battle if white invades.

Diagram1