100% Merino Light


¥9,000(Tax included)


Heavy Duty Pure Merino Wool

The 100% Merino Sleeveless offers extreme comfort and ease of movement and uses our proprietary Merino Wool Light (145-155g/m2), the thinnest fabric in our Merino Wool lineup. Also recommended to wear it with Yamatomichi Trail Shirts.

The 100% pure Merino wool makes your hiking more comfortable as they help to regulate both temperature and humidity and keep unwanted odors to a minimum.

Additionally, merino wool usually cannot be tumble-dried as it may cause shrinkage and deformation. However, with our proprietary 100% Merino Light fabric, tumble-drying is possible at a low temperature setting (maximum 60°C).

To prevent shrinking, the fabric is heat treated which creates a slub texture on the surface, giving it that well-worn vintage T-shirt look.

Updated Fabric

Our 2023 knit merino wool is less prone to twisting (structural disfiguration) with the use of a new yarn manufacturing process called compact spinning.
*For more detailed information, please refer to “Materials”.


Jay Blue
Purple Haze
Gray Marl
Charcoal Marl


Made in Akita, Japan

100% Merino Wool 145-155g/㎡
76g (Size S)
85g (Size M)
91g (Size L)
WOMEN | S / M / L

Product Story

Love for Merino

Akira Natsume, Yamatomichi Founder

I really love Merino fabrics. They are almost odor-free even when I sweat, comfortable, and keep the humidity and temperature constant even if I get soaked. Merino wool has so many natural and excellent properties that make it perfect for hiking.

When thru-hiking over a longer period, I really start to feel that I myself am part of nature. It is like my body somehow resonates and links with the greatness of my surroundings.

Deep in the mountains, as I walk, run, sweat, sleep, wake up and walk again, Merino wool is always my choice. For me, it connects my body with nature, and that is why I continue to focus on items made of pure Merino wool without any added synthetic fibers.

I have spent so much time and money developing our proprietary merino fabric. Why? This is all because of my love for merino!

Yuriko Hori, wearing the Green color.

Form and Function

Where the 100% Merino Light Stands

Though this product dries slower than general synthetic base layer T-shirts, it is less likely to cause hypothermia caused by the evaporation of sweat or other moisture. In other words, the new 100% Merino Light series focuses on moisture absorption rather than quick-drying, and on thermal insulation rather than cooling properties.

Recommended Scenes

When the temperature changes drastically
Wool is good at maintaining a constant temperature inside the garment, keeping you dry and comfortable even in situations where temperatures can suddenly change.

When worn under an outer shell
Synthetic base layers with low moisture absorption can feel very humid and stuffy. On the other hand, our 100% Merino’s superior moisture absorption properties, will help to keep you dry and comfortable when worn under an outer shell.

When worn for long hours
Synthetic clothes often become smelly relatively early on, even if they are deodorant finished. Wools, on the other hand, naturally eliminate odor when the fabric dries even after being soaked in sweat. This powerful anti-odor performance allows you to keep moving day after day, relatively comfortably without smelling too bad. For details, please visit HERE (Currently available in Japanese only).

When packing capacity is limited
Our Merino wool products can be worn in various situations for long hours without getting too smelly, minimizing the need for extra clothes in your backpack.

Naturally Odor Resistant

Wool base layers are chosen by many hikers for the material’s excellent odor-neutralizing performance. Some say it’s almost odor-free even after a week of heavy hiking, but we’ll let you (and your friends) be the judge of that…

Wool’s deodorant mechanism is still a mystery. One theory has it that wool absorbs a large amount of odor-causing elements, and consequently, the odor is minimized to the level that cannot be detected by the sense of smell. We will conduct our own experiments and tests in the future.

Great Moisture Control

Wool is great to help you keep warm and cool as it naturally controls the moisture level within the clothes, always keeping you comfortable throughout the year.

Wool is great to help you keep warm and cool as it naturally controls the moisture level within the clothes, always keeping you comfortable throughout the year.

Even Warm When Wet

First, when wool absorbs moisture, the thermal phenomenon called “absorption heat” is generated. Secondly, its excellent insulation properties (low thermal conductivity) prevent the body heat from being lowered by evaporation. Also, the crimped fibers are bouncy and retain loft without crushing even when wet.
In addition, wool can absorb more moisture in between the fibers, always keeping the skin dry and comfortable.

Consequently, 100% Merino wool keeps you warm during the action, even in severe weather that makes you wet to the skin.

When fibers absorb moisture, the thermal phenomenon called “absorption heat” is generated. The wool’s adsorption heat performance is twenty times of polyester, and 2.5 times of cotton.

Tumble Dryable Pure Merino

Normally, Merino wool products cannot be tumble dried as the heat causes shrinkage and deformation of the fabric, but our proprietary 100% Merino wool can be tumble dried* at low temperatures (Upper limit of 60 Celsius).

This makes it better suited for long hikes and travels, as you can easily use dryers at laundromats and hotels.



The neckband seam is reinforced with a binding finish, attaching a strip of fabric from both shoulders to the back of the neck to cover the seam.


More Durable and Stable Quality

We have focused on using 100% merino wool without synthetic fibers. However, pure merino does have its setbacks; lack of strength, yarn breakage, and shrinkage after washing.

We made many improvements over the years, such as applying a hydrophilic finish to improve sweat absorption, pre-shrinking for tumble drying capabilities, using single yarn to improve durability and making the fabric 10% lighter for maximum comfort in the warmer seasons.

The 2023 model uses a new type of yarn made through a method called “compact spinning.” A method not often done with wool, fibers are condensed before twisted into yarn, resulting in a more smoother, stable and stronger yarn than our previous 2022 model.

Our proprietary fabric is produced in Bishu, the production area of wool garments in Japan, in cooperation with the spinning company, fabric factory, dyeing, and processing factory, and inspection organization. We continue our effort to innovate with new products and markets.

The fabric carries a unique texture created by prior heat treatment.

100% Merino Wool

Weight: 145-155g/m²
Yard count: 1/52
Bursting strength (JIS L1096A): 274kPa
*The value of the pressure when the rubber membrane tears the fabric as the membrane is continuously pressurized.Heat retention (JIS L1096A): 26%
*Energy loss when the fabric is placed on the heat source.

Why 100% Merino?

Wool is a natural material with various unique features such as temperature/moisture control, thermal insulation, and is naturally odor-resistant. All are developed by sheep to survive the harsh environment over time.

Merino wool comes from merino sheep and compared to other kinds of wool, merino fiber is finer, softer, and less scratchy, and hence even suitable for making underwear and baselayers.

All wool, including merino wool, is cool in summer and warm in winter. It is warm even when it’s wet, and practically odor-free even after many hours of wear.

While many other manufacturers add synthetic fibers to strengthen their Merino fabrics, we wanted to stick with 100% Merino to maximize the natural benefits of pure merino wool. Our merino will keep you dry even when it’s hot and humid and comfortable no matter the climate.

The above chart shows the comparison of moisture content ratio of three types of fabrics in a humid and hot environment (up, 30˚C with 90% humidity) and a more comfortable environment (down, 20˚C with 65% humidity).

In a humid and hot environment, the fiber with superior moisture absorption keeps you dry and comfortable. On the other hand, in dry conditions, it is more comfortable when the fiber provides a certain level of moisture without excessively absorbing available humidity. The difference of the moisture content ratio in the above chart indicates the moisture control performance: the greater the value is, the better the fabric’s moisture control performance is, therefore the larger percentage means better comfort.

The 100% merino fabric, as shown above, has a 6.8% moisture ratio difference. This means that our merino material can effectively control the moisture compared to the other fabrics, keeping you dry when it’s hot and humid while supplying a moderate amount of moisture when the humidity is low.
This is the reason why the merino wool is known as “a natural air conditioner”.

Merino Wool

Wool is a natural material with various unique features such as temperature/moisture control, thermal insulation, and anti-odor performance; all of them developed by sheep to survive the harsh environment over time.

Merino wool comes from merino sheep and compared to other kinds of wool, merino fiber is finer, softer, and less scratchy, and hence even suitable for making underwear.

All wools, including merino wool, are cool in summer and warm in winter. It is warm even when it’s wet, and practically odor-free even after many hours of wear.

Wool’s Structure

The wool’s fiber is composed of amino acid-based protein, just like human hair and skin. The surface is called the “scale”, which is similar to a fish scale, and the inner part is the “cortex”.
The cortex is composed of the ortho-cortex and para-cortex, each with different moisture absorption performances. Because each of them differs in property, the combination of ortho and para cortexes makes the fiber “crimped”.
This crimped structure produces the wool’s unique features such as moisture/temperature control property and thermal insulation performance, avoiding the coldness caused by sweat.

Read More

Disadvantages of Wool

As explained above, wool or merino wool has various features and functions, but it is not flawless.

  • Easily absorbs moisture and becomes heavy
    Wool can get quite heavy as it is great at absorbing moisture. This also means that wool takes longer to dry than synthetic fibers, but compared to cotton, it actually dries faster.
  • Liked by insects
    Soft, natural fibers such as wool, cashmere, and silk are prone to damage by insects.
  • Easily damaged
    The relatively short fibers of wool mean that wool fabrics are easier damaged than synthetic and cotton fibers. However, small holes can easily be fixed with a bit of pure wool and a needle.
  • Shrinks easily
    Wool generally shrinks easily, even when shrink-proofed. To reduce shrinkage, after the wash, please spread the shirt well to return to its original shape and gently iron it.
  • Distortion
    When knitted wool fabrics are washed, the material is likely to distort diagonally because the yarned fibers absorb water, swell, and tend to untwist. Consequently, the shape of the shirt may distort slightly with washing.
  • Distinctive smell
    The wool comes from sheep and you may experience a distinctive animal-like smell coming from your t-shirt when damp. This smell usually disappears after the fabric dries.

The above information was compiled and edited based on the interview with the textile company and the research institute, and the reference book below:

Structure and Physical Properties of Wool, Japan Wool Industry Association, Seni Co., Ltd.


  • Kanade 161cm-51kg
    Size M (Navy)

    • Kanade 161cm-51kg
      Size M (Navy)

      • Nana 151cm-47kg
        Size S (Navy)

      • Eriko 158cm-47kg
        Size S (Navy)

      • Eriko 158cm-47kg
        Size M (Mustard 2022)

      • Kanade 161cm-56kg
        Size M (Red)

      • Kanade 161cm-56kg
        Size L (Charcoal Marl)

      • Hikaru 165cm-59kg
        Size M (Gray Marl)

      • Hikaru 165cm-59kg
        Size L (Jay Blue)

      • Yumiko 170cm-59kg
        Size L (Blue Gray 2022)

        • Nana 151cm-47kg
          Size S (Navy)

        • Eriko 158cm-47kg
          Size S (Navy)

        • Eriko 158cm-47kg
          Size M (Mustard 2022)

        • Kanade 161cm-56kg
          Size M (Red)

        • Kanade 161cm-56kg
          Size L (Charcoal Marl)

        • Hikaru 165cm-59kg
          Size M (Gray Marl)

        • Hikaru 165cm-59kg
          Size L (Jay Blue)

        • Yumiko 170cm-59kg
          Size L (Blue Gray 2022)

          推奨サイズ / Recommended Size

          Size S M L
          体重 / Weight
          42~49 47~56 54~62
          胸囲 / Chest
          78~84 82~90 86~94

          製品サイズ / Product Size


          Size S M L
          着丈 / Length 58.5 60.5 62.5
          肩巾 / Shoulder Width 32 34 36
          身巾 / Body Width 42 44 46
          裾巾 / Hem Width 41 43 45

          The fabric will stretch approximately 1 cm vertically when hung to dry from from the listed values.
          – The above values show the measurement when the item is brand-new and unwashed.
          – Due to the characteristics of elastic knit materials, the sizing may vary 1-2cm.
          – Due to the difference in the shrinkage tendency, there may be some individual differences in the measurements of the product.
          – Tumble-drying at low temperatures may cause more shrinkage than when dried by natural drying. The shrunk item will be restored by washing and line-drying again.
          – Iron with steam if shrunk after the wash and drying. Gently stretch the fabric while ironing for the best results.

          Our 100% Merino Light series have a wide-fit, standard-fit, and slim-fit: 100% Merino Light Sleeveless is slim-fit.


          Color Transfer

          When 100% Merino Charcoal, Marl or Navy is in contact with a white or light-colored shirt wet from rain or sweat, color may transfer and stain the shirt.


          Use tumble-dryer on low setting (60°C or lower).

          The tumble-drying may cause shrinkage and the length may be shortened by about 1-2cm, but it will be restored after washed again and line-dried.

          Care Instructions

          • This product is made of highly odor-resistant merino wool, which usually does not require a frequent wash.
          • The fabric uses shrink-proof pure merino wool. It is machine-washable by “Gentle Course” or “Hand Wash Course” with gentle water flow.
          • When you store the item, use mothballs and/or vacuum storage bags to keep out insects.
          • Merino’s fibers are short, and fuzz and pilling may appear, which can be removed by several washes.

          Please check our Care Instruction Page

          For more detailed tips on how to wash, store and restore the shrunk item, please visit the following link: Care Insturctions


          • We only accept payment by credit card. We currently do not accept payment via bank transfer from overseas accounts.
          • We accept the following Credit Cards: Visa, Master, American Express, and JCB.
          • To download your receipt, please click the link included in the Dispatch Notice, which we will send by email as soon as the items are dispatched.


          • Order Confirmation will be sent after the order.
          • The items will be dispatched within 3 days after the payment is confirmed.
          • The dispatch notice will be sent by email as soon as the items are dispatched.
          • The delivery may be delayed by unforeseeable reasons such as natural disasters and other logistics issues. We appreciate your patience and understanding.
          • We cannot ship multiple orders in one package due to how our delivery system is currently set up.
          • We will ship to regions in North America, Oceania, and Europe (excluding Russia) via DHL. For regions in Asia, the Middle East, Central and South America, Africa, and Russia, we use EMS (International Express Mail Service) for shipping.
          • Shipping fees and delivery times vary depending on the shipping destination as well as the size and weight of the items.

          Size Exchange

          • Overseas customers who need to change the size of their order, should note that the time needed for shipping will vary greatly depending on your country of residence.
          • We only accept exchanges when the item is unused (except for fitting).
          • If you wish to exchange the size of the item, please contact us within seven days of receiving your order.
          • Exchanges can only be made for the same color in a different size.
          • If the size you wish is out of stock, we will suggest a different color.
          • If the product is out of stock, we may simply have to ship the item back to you.
          • All shipping costs to be carried by the customer.
          • We will only send the exchanged item to you, upon receipt of return shipping cost via PayPal.
          • Please be aware that some countries charge customs duties depending on the price of the item.
          • We are unable to answer any questions on local customs. Please contact your local customs bureau.


          A natural fiber, merino wool has wonderful properties such as excellent temperature and humidity control and deodorant performances, but it also has a weakness; yarns are likely to break and develop holes due to abusive use and moth eating.

          For inquiries on repairing holes or products damaged over time, please feel free to contact us from the “Repair” section of the SUPPORT page.

          Needle Felting

          Holes in merino wool cut-and-sewn products caused by thread breakage or moth bites can be repaired by felting, a technique to patch the hole with the raw wool using a special needle. You can repair by yourself, and Yamatomichi also offers felting repair services using raw wool of the same color as the product.

          For more details of felting and how we repair the merino items, visit Yamatomichi JOURNALS “#1 Repairing Holes in Merino Wool“.