Among the basics Kihon, Jo-Ha-Kyu is perhaps one of the more interesting concepts to understand and apply in practice. This article explores the details from several perspectives.
The Kanji for Jo-Ha-Kyu is "序破急". Examining each Kanji character, they are respectively "Preface or Beginning", "Revelation" and "Suddenness". Put together, they express the pacing and building up of events to an outcome.
In Iaido waza, this translates into an inherent rhythm for each action and transition within the waza. Why is there a need for Jo-Ha-Kyu instead of say, going through the motions of the waza (consistently/fast/etc.) and be done with it?
Practice mechanism - Waza practice involves deliberate controlled practice. In a sense, JoHaKyu facilitates defining the rhythm for the waza. At the surface, it seems the controlled set of motions would appear to be too controlled and slow. However, consider the purpose of a Waza - it is a set of predefined actions for practice. Over time as the Iaidoka's proficiency increases, one would then be to vary the pace of Jo Ha Kyu at will to suit particular situational needs.
Zanshin - One aspect of waza practice involves the application of Zanshin as well. JoHaKyu ties in nicely with Zanshin. Imagine slowly observing the situation after making a nukitsuke (draw to cut), followed by Chiburui.
Body mechanics - Like the ebb and flow of the tide, JoHaKyu facilitates the generation and application of the necessary level of strength, at required phases of a Waza. Imagine doing a nukitsuke in Mae Seiza, but with the hand tensed up as if doing the cut itself - that would be overly tense to be effective from the get-go.
Wrapping up, JoHaKyu involves a transient nature, and the perspectives offered above are but a simple introduction, to begin with. To better appreciate JoHaKyu, it requires both practice and reviewing the Wazas overtime.
We hope this article, short as it may be, has been an informative read. Till then, stay safe.