Individual
The leader with the old mouth is the one who has said many things. That makes them different from everyone, an individual.
Imagine that leader's old mouth saying things that make the old man stand apart from the others. They are individual from everyone else.
こ
None
None
As an individual, one must teach all the 子s (こ) their way. Their individual way.
"You must be your own individual. Don't be a sheeple," he says to the 子s.