I found out about Mike Rother's Toyota Kata from my boss--he had recommended it to another one of my coworkers, so I heard quite a bit about the book from the two of them and decided I had to read it myself.
The book is about how Toyota has created a culture of continuous improvement through what the author has decided to call "katas." The katas are so ingrained in the Toyota culture that they do not talk about them, which is why it's an unfamiliar topic for Americans. Rother discusses two katas: the improvement kata and the coaching kata. The improvement kata is a group of patterns used to make striving and scientific working a daily habit. Practicing the improvement kata helps people get better at navigating unknown territory and meeting challenges in business and in any other endeavor. To be effective, the improvement kata should be practiced and coached every day. The coaching kata is how managers and supervisors teach and reinforce the improvement kata with their employees.
I'm familiar with the PCDA approach to improvement, but it was interesting to read how Toyota sets target conditions to strive for because the focus is on how a process should operate, not just setting a quantifiable result. The idea is that by understanding the current condition and target condition, we can identify the problems well enough that the next step will become clear. The key is to work on only one problem at a time so the cause-effect relationship is maintained.
The coaching kata was fascinating to me; in order to be able to coach, one must have been coached through the improvement kata previously. The coach needs to be familiar enough with the kata to know what the next step is. As the author described it, it initially seems like the coach or manager knows the answers to the questions he is asking his employee, but in fact, he is asking the questions because he knows the next step of the kata (and not necessarily the solution).
More information about the Toyota Kata can be found here.