Doing, Do
The leader samurai didn't become leader by sitting around not taking action. He got to where he is by doing.
Imagine the leader samurai doing things. He's doing more than anyone else, no one can keep up with what he's doing.
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He was doing things with sheep (し). He is the leader of the sheep clan, and he was able to do more with sheep than anyone else. That's why he's the leader.
Picture the leader samurai doing lots of sheep things. He's shearing sheep. He's feeding sheep. He's doing everything you could possibly do, because he's the sheep samurai.