No matter how urgent it is, the habit of saying 'Yes' too quickly is absolutely forbidden in negotiations.
Regardless of how much weight the concession carries in the negotiation, if it appears simple and easy, the other party will use it as an opportunity to lead the negotiation at their own pace and demand more.

--- p.32

In negotiations where interpersonal relationships are paramount, such as between spouses, children, or friends, the goal is not to focus on "what results have been achieved?" but rather "can we create better interpersonal relationships through this negotiation?"
Yes, that's right.
In a relationship, the more important question is 'How will we build a good relationship?' than the more obvious question of 'What kind of car will we buy?'
(…) Sometimes negotiation is about pursuing a losing outcome to improve long-term relationships without being obsessed with short-term gains.

--- p.46

Negotiation is not a fight, it is about working together to find a solution.
Those who negotiate without understanding this simple principle are likely to end up in a disaster where both sides end up going their separate ways.
The result of the catastrophe is that both you and I suffer losses, and in the end, no one wins.

--- p.50

We must not give up on negotiations because of apparent power disadvantage.
When it appears that one party is clearly at a disadvantage compared to the other party, many people lose the will to negotiate and end up negotiating in a way that leaves room for whatever happens.
But in fact, what causes negotiations to fail is not their weakness, but their attitude of giving up.

--- p.56

When negotiating, there are times when it is difficult to make a decision right away.
(…) The stress of having to decide everything in this one negotiation today is a factor that infinitely lowers one’s position in the negotiation.
In such cases, you end up making unreasonable concessions and end up being dragged around by the other party.
Therefore, especially if the negotiations are going in a way that is unfavorable to you, you should blow the whistle for a break without delay.
And we must be able to turn the tide in the next negotiation.

--- p.61

Before coming to the department store, I, a so-called negotiation expert, realized that my assumption that "sale items have low margins, so there's no room for price negotiation" was seriously flawed.
It was only then that I realized that negotiating when purchasing items that were displayed in large quantities in the hopes of selling them off quickly during a sale period could be easier than when selling them at full price.
Just as it's essential to question the other party's words and actions, especially in negotiations, by asking, "What are their underlying intentions?", it's also essential to test the accuracy of your own assumptions about what the other party is thinking before sitting down at the negotiating table.

--- p.77

To negotiate effectively, you must understand that even seemingly similar negotiation subjects can have different values ​​depending on the other party.
Keeping these facts in mind can help you conclude any negotiation on much more favorable terms than you might have anticipated.

--- p.104)

Experienced negotiators usually categorize various issues into three categories during the negotiation preparation stage:
The first is ‘absolutely non-negotiable issues.’
This is an issue that cannot be compromised at any cost, and it is better to break off negotiations than to compromise on this issue.
The second is 'a matter that can be exchanged for the other party's concessions if we try our best to keep it, but must obtain them.'
The third is ‘a matter in which it is okay to give in appropriately when the other party demands concessions.’
This issue can be freely discussed during negotiations with the other party, and one may even make a concession first to induce the other party to make a concession.

--- p.111

I have a rule that I always follow when negotiating.
It means that you will never lie by making up stories that are not true.
If a lie is exposed, your credibility as a negotiator will be irreparably damaged.
In negotiations, losing trust in the other party is a huge weakness.
Another rule of thumb when negotiating is to never reveal any information that is detrimental to you.
If necessary, select only partial truths and tell them to the other person.
Because I have learned through experience that telling only partial truths is much more effective than lying, and it doesn't cause any problems later on.
The negotiating table is different from the witness stand in a courtroom.
I don't need to tell the other person everything I have from beginning to end, and I shouldn't tell them anything.

--- p.145

During negotiations, we often see scenes where negotiations break down or conflicts between the two parties escalate for trivial reasons that cannot be rationally explained.
This happens more often, especially when people from our country negotiate with each other.
As American consultants have discovered, Koreans, who are face-conscious and emotional, will react emotionally when they feel slighted by the other party during a negotiation, regardless of the outcome.
When this kind of atmosphere is created, both parties begin to expend useless effort and emotions.
As a result, both parties suffer equal damage or have their relationships severed beyond repair due to the breakdown of negotiations.

--- p.259

Most people set limits on what they will compromise when preparing for a negotiation.
But even if it is a concession prepared like this, it cannot be given unless the other party asks for it.
Rather than expecting the other party to do something, negotiations need to be conducted by finding out what the other party is prepared to give and asking for it.

--- p.311