The key move here is the descent at
, threatening to connect underneath while making shape. After
, Black has two eyes: at the circled point, and in the corner.
If Black draws back to
, White plays hane at
and reduces the black group to an L-Group (White can indeed not play at the marked point). With no weaknesses to exploit, Black is dead.
Authors
Main line: HashimotoUtaro
Variations: Dieter