Light Alpha Armsleeves


¥ 5,500 Tax Included


Ultralight Alpha Armsleeves

The Light Alpha Armsleeves is made of Polartec Alpha Direct, a material that balances breathability and insulation very well. We designed it so that you can regulate your body temperature by removing or putting on the Armsleeves, making it ideal for UL hiking, fast packing, and trail running.

Its soft and lightweight texture provides maximum comfort while keeping your arm movement unrestricted. It pairs well with sleeveless or short-sleeve base layers or our mid-layer products such as the Alpha Vest or Alpha Haramaki.

To avoid throwing away surplus materials, The Light Alpha Armsleeves are made from upcycling Light Alpha Tights scraps.

Light Alpha Armsleeves Features

  • Excellent balance of breathability and insulation with Polartec Alpha Direct
  • Lightweight and compact
  • Draw cord for quick adjustments
  • Easy Layering while on the move
  • Maintains insulation even when wet
  • Thumb holes
  • Perfect with our Alpha Vest or Alpha Haramaki


Light Gray
Glacier White


Made in Miyagi, Japan

Polartec Alpha Direct (100% Polyester) 85g/m²
37g (Size S)
40g (Size M)

Product Story

Our take on Active-insulation

Takahiro Watanabe, Yamatomichi Laboratory

We had a project to make a product from surplus Polartec Alpha Direct materials, which led to the development of the Alpha Direct Armsleeves.
I only occasionally use arm sleeves, and when I do, I opt to use traditional compression type arm sleeves, primarily to help arm fatigue, UV protection and to add a bit of insulation. However, traditional arm sleeves can be somewhat inconvenient to put on/put off. It is even worse when you have a watch on. With that in mind, traditional arm sleeves weren’t a very appealing piece of equipment to me.
When I first got my hands on the prototype for our Alpha Direct Arm sleeves, I found it interesting as a piece of lightweight insulation tool but had doubts whether this would be accepted in the market, since it was so different from traditional arm sleeves.
My perception immediately changed after testing them. I often trail run, and in temperatures around 10 degrees, I sometimes venture out with just a base layer. However, to be prepared for the unexpected, I’ve been making sure to take lightweight mid-layers like the Alpha Vest or Alpha Haramaki as backup. Traditional long sleeve mid-layers are usually heavier and inconvenient to put on/take off, making it difficult to adjust layering while on the move.

Takahiro Watanabe, wearing the Black color.

The Alpha Direct arm sleeves are easy to put on and provide you with insulation exactly where you need it. By leaving the armpits open, it allows you to maintain warmth without overheating. Quickly roll them down if it gets too hot. The lightweight design allows for all-day comfort and even when combined with the Alpha Vest, they’re significantly lighter than long sleeved mid-layers.
During a summer trip to the Northern Alps in Japan, I left my sleeping bag behind and took an Alpha Vest, Light Alpha Arm Sleeves, Light Alpha Tights and UL All-weather Pants. Even without a sleeping bag, I was able to stay warm in my tent in 10-degree temperatures at night.
In single-digit temperature glaciers of the European Alps, I wore nothing but a DF Mesh Merino base layer, paired with the Alpha Vest and Light Alpha Arm Sleeves while hiking. Not only was I able to stay warm, I never overheated even when the sun was shining in mid-day.
Our founding father, Akira Natsume and the development team refined the prototype, prioritizing easy one-handed adjustments and anti-slip features. Despite its simplicity, the Light Alpha Armsleeves carries unlimited layering possibilities, making them an exciting choice for aggressive and active hikers.

Read More

Product Voice

A new friend
Light Alpha Armsleeves

Akira Natsume, Yamatomichi Founder and Takahiro Watanabe, Yamatomichi laboratory

Yamatomichi Founder, Akira and the head of Yamatomichi Laboratory, Takahiro will explain the appeal of the new product, Light Alpha Armsleeves, while sharing field test stories.


Alpha Vest and Alpha Haramaki

We recommend the Light Alpha Armsleeves with our Alpha Vest or the Alpha Haramaki. Adjust the level of insulation you want freely while on the move. The Light Alpha Arm sleeves are so light, you can roll it down to your wrists when hot, and not feel the weight.

Combine with a base layer or a trail shirt.

In situations where a short-sleeve or sleeveless base layer alone leaves you feeling cold, but adding a mid-layer makes you too warm, the highly breathable Light Alpha Armsleeves is the perfect solution.

Also, our short-sleeve trail shirts act as an effective windbreaker, creating a layer to retain body heat from wind, allowing you to stay active even in colder temperatures.

Kaori Kobayashi 170cm-53kg
Light Alpha Armsleeves (Size S / Light Gray)
DF Mesh Merino Sleeveless (Size Women L / Slate Blue)
5-Pocket Shorts (Size L / Woodrose)

Tomohiro Kobayashi 181cm-72kg
Light Alpha Armsleeves (Size M / Black)
Bamboo Short Sleeve Shirt (Size Men L / Indigo)
5-Pocket Shorts (Size Men L / Glacier White)

Form and Fucntion

Thermal Comparison

Although it is not as warm as 1000 fill power down, the slightly thick Polartec Alpha Direct (136g/m2) is one of the best insulators available. The Alpha Direct can be used not only in action but also when resting, always keeping you warm.

The chart compares the 1000 fill power down and other insulators used in thermal clothes on the market:

  • Heat retention is measured by JIS L 1096 A method, in Yamatomichi in-house test. The heat insulation property is measured by the amount of energy consumed by the heat-generating element to maintain its temperature.
    The maximum value is 100%.
  • The values of Polartec and Primaloft fabrics are the manufacturers’ catalog specs. Other fabrics’ values are measured by Yamatomichi. 1000 fill power down includes its 7 denier nylon outer and lining.


Dries quickly even when wet with sweat.

The chart compares the fast-drying performance of middle layer products*. It is shown that Alpha Direct is not as fast-dry as the extremely fast-drying Shadow Rip (UL Shirt), but the moisture content after spin-dry is much lower than that of wool and other fabrics, and even when wet, it dries quickly if lightly wrung out or worn for some time:

*Tested by Yamatomichi. Compared the difference of the water content after completely wet and 15 minutes of spin-dry. The larger the value, the higher the moisture content, meaning slower drying.


The upper opening is equipped with an elastic stretch cord for quick adjustments.

The thumb holes not only prevent the sleeves from rolling up but also provide moderate insulation to the hands.

Rubber lining on the inner side of the opening for extra grip.

Quick Layering

You can quickly adjust your layering to your body’s needs by pulling the Armsleeves up when cold and lowering it to your wrists when hot.

Super Compact and Lightweight

The Light Alpha Armsleeves are extremely lightweight, weighing only 37g in Size M, means you can carry it with you at all times without feeling weighed down.

Upcycled from Surplus Materials

To avoid throwing away surplus materials, The Light Alpha Armsleeves is made from upcycling Light Alpha Tights scraps.

This is the cutting diagram for Light Alpha Armsleeves and Light Alpha Tights. It’s worth noting that Light Alpha Armsleeves are created from the excess fabric that would typically be discarded during the production of Light Alpha Tights.


We had our experienced hiker friends review the Armsleeves for you to better understand the charm of the Light Alpha Armsleeves.


Polartec Alpha Direct

It is like a fleece with longer puffy hairs.

  • Excellent air-permeability and thermal performance
  • Outstanding lightness and packability
  • Polygiene treatment for semi-permanent antibacterial and odor-control

Conventional natural down and synthetic insulators tend to contain body moisture within the clothes and as a result, can be quite stuffy. Polartec Alpha Direct, on the other hand, is so air-permeable that it can be worn even during a high level of physical activity.

Alpha Direct is also treated by Polygiene odor control which safely reduces the microorganisms and bacteria by small amounts of silver ions, achieving antibacterial and deodorizing function that well exceeds the lifespan of ordinary garments.

Polartec Alpha Direct (100% Polyester) 85g/㎡

Bursting strength measured by JIS L 1096 A (In-house test)
Heat retention measured by JIS L 1096 A (In-house test)
Heat retention measured by ASTM F1868 (Catalog spec)
Min:0.50CLO, Max:0.80CLO


推奨サイズ / Recommended Size

Size S M
身長 / Height
150~167 165~175
体重 / Weight
42~61 59~69
ウエスト / Waist
60~80 74~84

製品サイズ/Product Size

M size is designed for men’s wear, and S size is intended for women’s wear.

Size S M
総丈 / Length 46 54
上腕巾 / Bicep Circumference 12.5 14.5
袖口巾 / Sleeve Opening 8 9

M size is designed for men’s wear, and S size is intended for women’s wear.

Choosing a size

  • Mサイズは男性、Sサイズは女性の着用を想定しています。
  • サイズ選びに迷った場合は上記「上腕巾」を参考にしてください。上腕の最も太い位置の周囲長(上腕最大囲)を計測し、2で割った数値が上腕巾です。上腕最大囲が28cmの場合は28÷2=14cmとなり、Mサイズをお勧めします。


Used 3 seasons


Care Instructions

  • Machine wash, below at 30°C, Use neutral detergent.
  • Wash separately or use a laundry net bag.
  • Do not bleach. Do not use fabric softener.
  • Dry flat in the shade to prevent stretching under its own weight.
  • When using a dryer, use a low-temperature setting (60°C or lower).
  • Do not dry-clean.
  • Do not iron.
  • If fluff is noticeable at the time of purchase, please wash once.


  • 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.


We accept repairs for all of our Yamatomichi products. For inquiries on repair services including patching the holes, repairing with extra components, or fixing the items damaged over time, please feel free to contact us from the “Repair” section of the SUPPORT page.