What Kaizen Means: The Word, Its Origins and Its Core Ideas

Kaizen shows up in a lot of places once you start noticing it: on factory walls, in hospital quality programs, in productivity books and on sticky notes next to someone's monitor. It is usually translated as "continuous improvement," and that is a fair start. The idea behind it, though, is more specific and more practical than a slogan about getting better.

This guide explains what the word means, how it entered English-language management, and the handful of ideas that separate real kaizen from a vague promise to improve. If you are new to the topic, this is the place to start.

What the word means

At its simplest, kaizen means improvement. Masaaki Imai, the author who brought the term to Western managers, defined it broadly. In a definition quoted by the Kaizen Institute, the organization he founded, he says it means continuing improvement in personal life, home life, social life and working life, and that in the workplace it means "continuing improvement involving everyone – managers and workers alike."

The Lean Enterprise Institute (LEI), a nonprofit that publishes widely on lean thinking, describes kaizen as a Japanese word that means "continuous improvement" and says it "aims to make small, incremental improvements in processes and systems." Two features stand out in both descriptions. The changes are small and ongoing, and everyone takes part. Neither description is about a single big project or a single expert.

How the term reached English-language management

Most Western managers met the word through a book. Imai's Kaizen: The Key to Japan's Competitive Success introduced the term to the Western world, according to the Kaizen Institute, whose timeline dates that introduction to 1986. LEI says the same thing in its own words: the kaizen philosophy "was first introduced to the world by Masaaki Imai in 1986."

It helps to be precise about what Imai did. He did not invent the Japanese word. What he did was present kaizen to English-language readers as a systematic management approach, drawing on practices Japanese companies had been developing for decades. The Kaizen Institute's history says Imai was born in Tokyo in 1930, worked with the Japan Productivity Center in the United States in the 1950s, accompanying Japanese executives on visits to American manufacturers, and in the 1980s worked internationally with Taiichi Ohno to spread the message of the Toyota Production System.

Where the practice came from

The methods Imai described grew up in postwar Japanese industry. Ronald Moen's history of the improvement cycle, published by the W. Edwards Deming Institute, notes that the Plan-Do-Check-Act cycle, the seven basic quality tools (check sheets, histograms, Pareto charts, fishbone diagrams, graphs, scatter diagrams and stratification) and a reporting format called the QC story together "became the foundation for improvement (kaizen) in Japan."

Toyota is the best-known practitioner. The company's official description of the Toyota Production System says the system is pursued in all areas of the company and that "all employees implement daily incremental kaizen." Toyota calls kaizen on work "the bedrock of jidoka," one of the two pillars of its production system, and makes the point bluntly: however good machines, robots or IT become, "they can't evolve any further on their own. Only humans can implement kaizen for the sake of evolution."

The core ideas

Kaizen is less a single tool than a handful of ideas that work together.

1. Small and continuous. LEI describes kaizen as "not a one-time fix but a long-term approach." Many small gains, made steadily, add up over time.
2. Everyone takes part. In LEI's description, the kaizen process encourages employees to identify areas for improvement and come up with practical solutions that can be implemented quickly. The people closest to the work usually see its problems first.
3. A learning cycle. LEI says the kaizen process "is based on the PDCA (Plan-Do-Check-Act) cycles": identify an area to improve, plan a change, try it, check the results and decide what to do next.
4. A standard to improve from. LEI quotes Taiichi Ohno: "There can be no kaizen without a standard." Without a stable, repeatable way of working, LEI warns, teams perform kaizen on top of chaos and the gains rapidly vanish. Once a team achieves a measurable gain, it updates the standard so the gain sticks.
5. Removing waste and strain. Toyota describes eliminating "waste, inconsistencies, and unreasonable requirements," known in Japanese as muda, mura and muri. The last one matters: kaizen is meant to make work easier for people, not just faster.

Kaizen and its bigger cousin, kaikaku

Not every improvement is small. LEI uses the term kaikaku for "radical, revolutionary improvement of a value stream," such as moving equipment over a weekend so that products once made in batches are built in single-piece flow in a compact cell. It notes that kaikaku is also called breakthrough kaizen, in comparison with more gradual, step-by-step kaizen.

Between the two sits the kaizen event, sometimes called a kaizen blitz or kaizen workshop. LEI says these events commonly last five days, during which a team identifies and implements a significant improvement in a process. LEI considers them excellent for building capability and making substantial changes rapidly, but cautions that leaders should not rely on them alone, because steady daily kaizen is what develops frontline problem-solving capability.

What it can look like day to day

Here is a hypothetical example. Imagine a four-person print shop where jobs keep getting delayed because nobody can find the right paper stock. On Monday, the team agrees to try one small change: labeled shelves with a minimum stock line for the five most-used papers. For two weeks, they jot down every time someone has to hunt for paper. If the hunting drops, they write the new shelf layout into their opening checklist, which becomes the new standard. Then they pick the next annoyance.

Nothing in that example requires a consultant, software or a budget. It requires a clear problem, a small change, a way to tell whether it helped, and the habit of doing it again.

What kaizen is not

Kaizen is easy to imitate badly. LEI lists several failure modes it sees with kaizen events, and they apply to kaizen generally:

• Counting activity instead of results, such as tracking the number of kaizen events held rather than meaningful measures like safety, cost, quality and delivery.
• Gains that disappear as people drift back to the old way of working.
• Leaving frontline workers out, so specialists far from day-to-day operations lead the improvement instead of the people who do the work.

If you notice any of these, the fix is usually to return to the basics above: a clear standard, small tested changes and real involvement from the people doing the work.

Key takeaways

• Kaizen means improvement; in management it means continuing, incremental improvement involving everyone.
• Masaaki Imai introduced kaizen to Western management with his 1986 book; he popularized the term rather than inventing the Japanese word.
• The practice grew from postwar Japanese quality methods, including the PDCA cycle, and is central to the Toyota Production System.
• Kaizen depends on a stable standard to improve from, and each gain should update that standard.
• Breakthrough change (kaikaku) and kaizen events have their place, but daily kaizen builds lasting capability.

Sources

• Kaizen Institute, What is KAIZEN
• Lean Enterprise Institute, Kaizen: A Resource Guide
• Lean Enterprise Institute, Kaikaku
• Toyota Motor Corporation, Toyota Production System
• Ronald Moen, Foundation and History of the PDSA Cycle (The W. Edwards Deming Institute)