I have incorporated Mr. Kawaguichi's summary into my own work with children, especially teens. Rather than attacking an issue or disagreement head on (force with force), I am far more efficient with the going-with-the-energy approach. A child complains to his father than he had said he was going to shoot some hoops with him after supper, but the Dad had to sweep out the garage first. The judo approach was to ask the son for a solution to the dilemma, as he (the Dad) definitely wanted to play, and daylight was running out. The boy suggested he could help the Dad do the sweeping, as long as the Dad promised to shoot hoops, even if got dark. Perfect.
A daughter, returning home on vacation from her first semester from college was concerned about curfews. In her first semester in college, she had no curfew, and didn't want to be treated like a baby at home. A karate approach would be to tell her tough luck- deal with it. The judo approach was to address her objections and figure out a solution. “I agree that a curfew seems to be a step backward. However, when you mother gets up in the middle of the night to go to the bathroom, and you’re not back, she’ll never get back to sleep. What shall we do?” She suggested that regardless of how late she anticipated coming home, even 3 A.M., she would keep her self-imposed "curfew". If she had decided to spend the night at the friend's house, she would call no later than 1:00. The family later reported that although they were initially nervous about the compromise, she kept her word. As a side note, they were amused that despite the no-curfew agreement, she was usually home around midnight.
Obviously there are times when the parent has to pull out the because-I-told-you-so card, but the joy of dealing with issues by going with the other person's "energy" adding a few twists or flips of our own is the superior martial art of parenting.