The Birth Story of Moisture-Absorbing Heat-Generating Fiber | How a Revolutionary Winter Undergarment That Defined the Heisei Era Was Created

2025-12-12

Introduction

On a cold winter morning, you casually put on a thin undershirt. Yet it’s surprisingly warm. The “moisture-absorbing heat-generating fiber” undergarment, now taken for granted, was born through the extraordinary passion and challenges of Japanese engineers.

How was this revolutionary product, which became a mega-hit of the Heisei era, created? Let us share the story of developers who dreamed of changing the world amid the harsh economic climate following the burst of the bubble economy.

What Is Moisture-Absorbing Heat-Generating Fiber? Its Revolutionary Mechanism

The Mystery of Water Vapor Turning into Heat

The greatest feature of moisture-absorbing heat-generating fiber lies in its innovative mechanism of absorbing water vapor released from the body and generating heat.

The human body constantly releases water vapor. When special fibers absorb this invisible water vapor, kinetic energy converts to thermal energy as water molecules adhere to the fibers. This is the mechanism of moisture-absorption heat generation.

Differences from Traditional Cold-Weather Clothing

Previous winter undergarments primarily maintained warmth by enhancing heat retention. The concept was to prevent body heat dissipation by creating thick fabrics or air layers.

However, moisture-absorbing heat-generating fiber took an entirely different approach. It was a revolutionary shift in thinking: thin yet warm, or rather, generating heat on its own.

The Originator Was a Surprising Sports Equipment Manufacturer Engineer

Inspiration from Ski Wear Development

The first to conceive this revolutionary undergarment was not a major apparel manufacturer, but a developer at a sports equipment company handling ski wear.

While confronting the extreme cold of skiing, they pursued the ideal of “thin, lightweight, yet warm wear.” Skiing produces large amounts of sweat through intense exercise. In addressing the problem of sweat cooling and stealing body heat, the idea emerged: could moisture be utilized as a heat source instead?

Unconventional Thinking

The innovative power unique to a sports manufacturer, unconstrained by conventional wisdom in the textile and apparel industries, became the driving force that created this innovation.

They broke the stereotype that “cold protection requires heavy clothing” and proposed the entirely new concept of “converting water vapor into heat.” This was truly a revolutionary idea that overturned industry conventions.

Innovation Born from Post-Bubble Economic Hardship

Crisis in Japanese Manufacturing

Following the burst of the bubble economy in the early 1990s, Japanese manufacturing faced a serious situation.

The apparel industry was no exception. The domestic textile industry continued to shrink as overseas products with lower labor costs captured the market. Many factories closed, and engineers harbored anxieties about the future.

Challenge Born from Adversity

However, precisely because of these harsh circumstances, engineers strengthened their resolve to “create products that would amaze the world.”

They couldn’t win on price competition. Then they had to compete on technology. The challenge began to create innovative products unlike anything in the world, bringing together the finest of Japanese textile technology.

Development Difficulties and Engineers’ Passion

The High Wall from Theory to Practical Application

The phenomenon of moisture-absorption heat generation itself had been scientifically known for some time. However, commercializing it as practical clothing was an extremely difficult challenge.

Selection of fiber materials, knitting methods, processing techniques, and establishment of mass production technology. Each process required unprecedented technological development. Painstaking work continued, repeatedly failing, creating prototypes, and making improvements.

Teamwork and Industry-Academia Collaboration

This development involved cooperation from many specialists: textile manufacturers, material manufacturers, and university research institutions.

Experts from various fields pooled their wisdom and cleared technical challenges one by one. It was a moment when the strengths of Japanese manufacturing—close collaboration and high technological capability—came to fruition.

The Dream of Changing the World

What supported the development team was a grand dream beyond mere product development.

The passion to “change winter for people worldwide with this technology” and “demonstrate Japanese technological capability to the world” became the driving force to overcome difficulties. Engineers tackled development with a strong sense of mission that they were making history.

Market Launch and Consumer Response

Initially Skeptical Market

When the product first launched to market, consumer response was not necessarily enthusiastic.

Many voiced doubts: “Can a thin undershirt really be warm?” For consumers accustomed to traditional thick undergarments, the concept of thin yet warm was hard to believe.

Revolution Spread Through Word of Mouth

However, the excitement of actual users gradually changed the market.

Word of mouth spread: “It’s really warm,” “Surprisingly comfortable despite being thin.” Popularity gradually increased. It gained support especially from younger generations conscious of fashion and became established as a winter staple item.

Entry of Apparel Companies and Market Expansion

Ripple Effect Throughout the Industry

Following the pioneer manufacturer’s success, major apparel companies one after another began developing moisture-absorbing heat-generating fiber products.

Each company invested their own technologies, competing to release warmer and more comfortable products. This competition revitalized the entire market and promoted further technological evolution.

Becoming a Mega-Hit Product of the Heisei Era

Entering the 2000s, moisture-absorbing heat-generating fiber undergarments became completely established as winter necessities.

Sold on a scale of tens of millions, even hundreds of millions of pieces annually, they became one of the representative mega-hit products of the Heisei era. These reasonably priced, highly functional products were accepted across a wide range of ages and genders.

Social Impact Brought by Technological Innovation

Increased Fashion Freedom

The emergence of moisture-absorbing heat-generating fiber brought major changes to winter fashion.

People could stay warm without heavy clothing, enabling them to enjoy slim-silhouette fashion even in winter. This was particularly revolutionary for women.

Contribution to Energy Conservation

The spread of thin yet warm undergarments also contributed to reduced heating use.

People could stay comfortable even with slightly lower room temperatures, leading to reduced energy consumption in homes and offices. As environmental issues gained attention, this technology played a role in realizing an energy-conserving society.

Health Maintenance for the Elderly

For elderly people, lightweight yet warm undergarments held particularly important meaning.

Reduced physical burden from layering made movement easier, with reports of increased activity levels during winter. Health benefits such as reduced risk of heat shock also attracted attention.

Ongoing Technological Innovation

Addition of Further Functions

Beyond the basic moisture-absorption heat-generation function, manufacturers continue adding various added values.

They continue evolving to meet consumer needs: antibacterial and deodorizing functions, improved stretchability, better texture, and added quick-drying properties.

Expanding Applications

The application range of moisture-absorption heat-generation technology continues expanding beyond undergarments to socks, tights, gloves, and bedding.

Development for sportswear and outdoor equipment has also progressed, with utilization in various scenarios.

Japanese-Origin Technology Goes Global

Recognition in Global Markets

The moisture-absorbing heat-generating fiber technology born in Japan is now used worldwide.

It has gained particular popularity centered on Asian countries, becoming an indispensable item for winter cold protection. It has become an excellent example of demonstrating Japanese technological capability to the world.

Implications for Japanese Manufacturing

This success shows the path Japanese manufacturing should take: competing through technological innovation rather than price competition.

High technological capability, meticulous quality control, and an attitude of deeply understanding consumer needs. When these combine, products that amaze the world are born.

Conclusion: Revolution Born from Passion

Moisture-absorbing heat-generating fiber undergarments were revolutionary products created by the passion of engineers who wished to “change the world” amid harsh economic circumstances.

Innovative thinking unconstrained by convention, tenacity in facing difficulties, and high technological capability. These came together to create the mega-hit product representing the Heisei era.

Behind the thin yet warm undergarments we casually wear today lies such a passionate story. The dreams and passion of engineers make our winters comfortable.

This success has reaffirmed the possibilities of Japanese manufacturing. Even in harsh circumstances, with innovative ideas and technological capability, products that change the world can be created. The story of moisture-absorbing heat-generating fiber gives us such hope.

On cold winter mornings when you wear warm undergarments, remember the passion of the people who created this revolutionary technology. It is not merely clothing, but a crystallization of innovation that Japanese engineers proudly present to the world.