Toranaga: the wisest daimyo in Shogun

You should strive to make decisions that are logical, instead of emotional. Emotional decisions are rarely the correct ones. Instead try to look the situation from above. Play the situation, but remove yourself from the main role. Instead put some random person, but do not change the circumstances. Now, ask yourself what is the best move for the random person you've just placed. What should he do? How should he react? This helps a lot in making your decisions rational instead of emotional. Toranaga never really made an emotional decision, even if it was related to his closest circle.

No matter the situation, plan it in advance. Imagine you are playing chess, the best players are the ones who can plan (correctly) the most moves ahead. The better you are at 'predicting' the most likely outcomes, the more likely you are to win. Make a simulation about the situation, imagine that you do X, how will things play out? What will the counterparty do? What's your move then and so on. Usually if you are able to plan 2 moves ahead, that will make a big change. 5 is ideal. Toranaga made sure that everything was planned out to the closest detail.

Let's bring back the chess concept. You should not only plan for what your opponent will do next, but also plan your best response to this move. Well, if we are to go one step beyond, you should make such moves that your opponent doesn't have any good options. No matter what he does, you are still in better position. This was perfectly played out by Toranaga when he sent Mariko to Osaka. No matter how Ishido would have responded to the request of freeing the 'hostages', Toranaga would have gained an advantage. He simply gains better position WHEN his opponent responds (no matter HOW).

Let's recap:

1. Do not show your true intentions to your enemies
2. Do not make emotional decisions
3. Plan in advance
4. Make the best moves

That's only some of the lessons that could be extracted from this gigantic wisdom of power play.