Updating the "Pride of Cotton" with Japanese Spinning Technology: Behind the Scenes of Kamakura Shirts' "J-TECH" Development

Known by its beloved nickname "Kamakura Shirts," Maker's Shirt Kamakura Co., Ltd. has built its legacy on a dedication to "100% cotton," delivering superior comfort at a fair price. It's no surprise, then, that their top-selling product with the highest repeat customer rate is the "J-TECH" easy-care shirt series.

So, what prompted this legacy shirtmaker to venture into the world of easy-care shirts—a departure from its long-held philosophy? And what cutting-edge Japanese technology is woven into their fabric? We sat down with Director Takahiro Sano, the mastermind behind the "J-TECH" series, to get the inside story.

The "Dark Horse" Material Born from an "Adult's Pet Project"

Kamakura Shirts embarked on developing easy-care materials in 2014. The journey began when the company was selected for the Ministry of Economy, Trade and Industry's "Monodzukuri Supply Chain Reconstruction Support Project."

At the time, the company had no experience creating its own yarn from scratch in Japan. However, being chosen for this project—which aimed to bolster domestic manufacturing bases—they kicked off a joint development project with a leading domestic manufacturer's spinning mill in Okayama.

The main directive was to create something truly unique that no other company had. In response, the development team gathered various types of cotton from around the globe and engineered over 30 different prototype yarns by blending them.

"To be honest, we didn't have a clear goal of creating an easy-care material back then. With no firm deadline, the process of crafting a material we could be proud of felt like an 'adult's pet project,' and it was incredibly fun. Among the 30-some prototypes we made, one just happened to use a polyester-core yarn—it was a dark horse, so to speak."

After making shirts from the finished prototype fabric and conducting customer monitoring, the feedback was polarizing. While some expressed disappointment, saying they were "let down by the polyester blend," others offered high praise, noting, "It has a luster I've never seen before."

Based on these mixed reviews, the concept of "a shirt that offers easy-care convenience while maintaining the premium quality expected of Kamakura Shirts" was sparked. This became the launching point for the "J-TECH" series.

Functionality Born from a Polyester-Cotton Hybrid

The secret sauce behind the "J-TECH" fabric is its ability to deliver the comfort of cotton and the functionality of polyester simultaneously. This is all thanks to a specially structured yarn called "PALPA Premium."

It features a polyester core with high-quality cotton meticulously wrapped around it, creating what's known as a "core-sheath yarn" or "two-layered yarn."

Your typical wrinkle-resistant shirt is often either a 100% polyester fabric engineered for performance or a 100% cotton fabric treated with a resin coating. The former offers durability but poor moisture absorption, while the latter has a drawback: the chemical treatment wears off with repeated washing, diminishing its effectiveness.

In contrast, with "PALPA Premium," the surface that touches the skin is cotton, giving it the soft feel and moisture-wicking properties characteristic of natural fibers. At the same time, the central polyester core acts as a skeleton, providing excellent shape retention and wrinkle resistance.

"'PALPA Premium' combines the best of both polyester and cotton, and it never fails to deliver the comfort our customers expect from Kamakura Shirts. The cotton on the surface that touches the skin is an original blend of premium Indian cotton and high-grade Australian cotton, which boasts the world's highest level of whiteness."

This structure delivers a host of functional advantages. Let's start with its moisture-wicking and quick-drying capabilities. The outer cotton layer rapidly absorbs sweat, while the microscopic gaps between it and the central polyester core help diffuse and evaporate moisture. As a result, the fabric dries about 3.5 to 4 times faster than 100% cotton. This is why, even if you step into an air-conditioned room after sweating in the summer, your clothes won't feel chilly, keeping you dry and comfortable.

Additionally, the fabric also tackles common polyester problems like sheerness and stain-proneness. Polyester is oleophilic, meaning it attracts oils like sebum, but since this yarn is wrapped in cotton, stains wash out easily with a normal wash. Furthermore, by adjusting the density of the cotton wrap and the yarn's design, they've created a fabric that's less sheer.

Its resistance to pilling is another key feature. During the spinning process, the yarn is twisted to roll any fuzz inward. After weaving, it undergoes a 'singeing' process where the surface is passed over a flame. This two-pronged approach ensures the fabric maintains its smooth, beautiful finish for a long time.

Achieving these features is the result of painstaking trial and error and a tireless dedication to the manufacturing process. In a fashion industry dominated by fleeting trends, Kamakura Shirts' commitment to this kind of craftsmanship makes them a true rarity.

Throughout the three-year development period, the team prioritized 'human feeling' over hard data. Of course, the fabric was tested for shape retention and drying speed at official institutions, but at Kamakura Shirts, Sano himself conducted his own rigorous tests, personally wearing and repeatedly washing the shirts.

"I'll wash and wear a shirt about 20 times, checking for wrinkles and changes in texture with my own eyes. Even if it passes the numerical tests, if it doesn't *feel* like a Kamakura shirt when I wear it, we won't use it."

Countless prototypes were created, tweaking the balance between the thickness of the polyester core and the amount of cotton wrapped around it. Twisting the yarn tighter increases its strength but makes the texture stiff; twisting it looser makes it softer but more prone to fuzzing. Finding that perfect balance was a delicate task that relied on the instincts of skilled artisans and the development team.

They also refuse to compromise on sewing techniques. Most wrinkle-resistant shirts use an adhesive interlining (top-fuse) in the collar and cuffs. This stiffens the parts to prevent wrinkles. But Kamakura Shirts prioritizes comfort and a natural look, opting for a non-adhesive "floating interlining" instead.

Some models in the "J-TECH" series even use a hybrid approach, with a highly shape-retentive top-fuse interlining on the outside and a soft floating interlining on the side that touches the skin.

Using different interlinings for the front and back can easily cause a garment to lose its shape after washing due to different shrinkage rates, but this is where more meticulous adjustments came into play. The team marked 30-centimeter squares of fabric and measured their shrinkage after repeated washings. By fine-tuning the interlining's density and the amount of adhesive, they discovered the 'golden ratio' that allows the outer fabric and interlining to shrink together in perfect harmony, maintaining a beautiful shape.

The silhouette and collar shape are identical to their classic cotton shirts. The idea is to keep the signature look and feel of 'the usual Kamakura Shirt' while only upgrading its functionality. That's their philosophy.

A Long-Lasting Shirt is the Most Eco-Friendly Choice

The J-TECH series also makes a significant statement on the environmental front. The core of the yarn is made from polyester derived from recycled plastic bottles. The outer layer is a blend featuring high-whiteness Australian cotton, which minimizes the need for bleach and reduces water consumption during the cleaning process. This special structure also makes it possible to cut down on the use of cotton—a finite resource—by approximately 30%.

What's more, we can't overlook the benefits of a longer product lifespan and energy-saving maintenance. Cheaper non-iron shirts often end up in the trash after a short time due to fabric degradation and discoloration. But J-TECH fabric is exceptionally durable and resistant to losing its shape. The cotton surface also allows for effective stain removal, keeping the shirt white for longer. The result is a shirt you can wear and love for years, extending its life and delaying the disposal cycle.

The fact that these shirts require little to no ironing also contributes to a significant reduction in energy consumption over their lifecycle. If you wear the shirt once a week, you're saving the electricity and time spent on 52 ironing sessions a year.

When the line first launched, some long-time fans who were purists about 100% cotton were hesitant about the polyester blend. However, once they actually tried one on, they were amazed by the comfort and ease of care, and the number of converts who became repeat customers has been endless. Today, many customers come in specifically asking for J-TECH, making it a cornerstone of the brand.

J-TECH: A Name That Embodies the 'Made in Japan' Spirit

In January 2025, the company renamed its 'PALPA' series to 'J-TECH.' 'J' stands for Japan, while 'TECH' represents both Technology and Technique. The name reflects a strong desire to showcase the technical prowess and spirit of Japan's manufacturing regions to a global audience.

"To be truly global, you first have to value the local. We take outstanding local technology, elevate it to Japan Quality, and share it with the world. The name J-TECH embodies our commitment to supporting and preserving Japanese craftsmanship (monozukuri)."

It's said that Japan's self-sufficiency rate for apparel has now plummeted to the single digits. The reality is that the nation's textile industry is facing an existential crisis. The approach of meticulously identifying and resolving issues one by one—the antithesis of the mass-production, mass-disposal cycle—is a manufacturing philosophy born from the Japanese character, something difficult to replicate with overseas production.

Looking ahead, the company plans to further promote the wonders of J-TECH abroad, including outreach to international tourists visiting Japan. The day is not far off when people around the world will marvel at a shirt that so perfectly encapsulates Japanese technology and aesthetic sensibilities.

Kamakura Shirts didn't abandon its pride in cotton; instead, it embraced technology to preserve the very best qualities of the material, revolutionizing the easy-care shirt in the process.