Alpha Socks


¥4,500 Tax Included


Light, Breathable Sleep Socks

The material used is Polartec Alpha Direct, which offers an excellent balance between breathability and insulation. It’s thicker than down socks, yet lighter, providing just the right amount of warmth without causing excessive sweating, making it ideal for use as sleeping socks.

The Alpha Socks provides a snug, non-constricting fit around, ensuring that your feet are comfortably protected from the cold until morning.

To avoid throwing away surplus materials, The Alpha socks are made from upcycling Alpha Vest scraps.


Sage Gray


Made in Miyagi, Japan

Polartec Alpha Direct (100% Polyester) 136g/m²
34g (Size M)
38g (Size L)

Product Story

Best Friend for Bedtime

Akira Natsume, Yamatomichi Founder

I used to sleep with wool socks on because I tend to get cold feet, but now I wear Alpha Socks. Wool socks can feel a little restricted but with Alpha Socks I sleep with my feet feeling super comfortable. Except for the height of summer, I wear Alpha Socks to bed almost every night in almost all seasons.

The prototype of Alpha Socks was actually completed when the Light Alpha Tights were released in 2021. However, at first, I didn’t see the necessity for them, they didn’t quite replace my down socks.

But after trying them out for a season, it turned out that my initial assumption was completely wrong. They became an essential tool not only for the mountains but also for everyday life.

When thinking about hiking, while the warmth of down socks is desirable in the extreme cold of winter, for the three seasons of spring, summer, and autumn, their portability, lightweight nature, and comfortable breathability make them indispensable as sleep socks.

Additionally, due to the nature of the Polartec Alpha Direct material, when you put them on, they compress slightly. This means that when you need to make a quick trip from your tent to the restroom, you can even put your shoes on over them with a bit of effort.

Considering their lightweight and ease of use, I find them to be an extremely convenient tool.

September 2023

Read More

Product voice

Comfort everywhere

Akira Natsume, Yamatomichi Founder and Hidenori Maehara, Yamatomichi Kamakura Manager

In this video Akira and Hidenori will explain the concept behind the new product, Alpha Socks, as well as the intended usage scenarios.

Form and Function

Breathable Comfort

By using Polartec Alpha Direct, which offers excellent breathability, Alpha Socks provide comfortable sleep without completely trapping heat and moisture.

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.

Relaxed Fit

With a relaxed fit that doesn’t exert pressure, the Alpha Socks provides maximum comfort to your feet.

Quick-drying and Insulating

The Alpha Socks possesses excellent quick-drying capabilities and maintains consistent insulation even when wet.

The achart 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.

Lighter and More Compact Than Down Socks

Alpha Socks are lighter than typical down socks, weighing only 34g with size M, folded they’re about the size of a soda can.

Upcycled from Surplus Materials

To avoid throwing away surplus materials, The Arm Sleeves are made from upcycling Alpha Vest scraps.

This is the cutting diagram for Light Alpha Armsleeves and Light Alpha Tights. It shows that Light Alpha Armsleeves are made from excess fabric that would typically be discarded during the production of Light Alpha Tights.


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.

Shedding may occur overtime with use and frequent washing. This is due to the structure of the loft where hairs are directly implanted into the mesh fabric.

Used 3 seasons


Polartec Alpha Direct 85g/㎡

100% Polyester (63% recycled) bluesign® and OEKO-TEX® approved.

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:0.80CLO, Max:1.60CLO


推奨サイズ / Recommended Size

Size M L
足長 / Foot length
22.0 − 25.0 25.0 − 28.0

製品サイズ / Product Size

Size M L
A 18 20
B 13.5 14.5
C 13.5 14.5
D 16.5 23.5
E 17.5 25


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.