• Top 14 Best Japanese Men's Warm Innerwear to Buy Online 2020 - Tried and True! 1
  • Top 14 Best Japanese Men's Warm Innerwear to Buy Online 2020 - Tried and True! 2
  • Top 14 Best Japanese Men's Warm Innerwear to Buy Online 2020 - Tried and True! 3
  • Top 14 Best Japanese Men's Warm Innerwear to Buy Online 2020 - Tried and True! 4
  • Top 14 Best Japanese Men's Warm Innerwear to Buy Online 2020 - Tried and True! 5

Top 14 Best Japanese Men's Warm Innerwear to Buy Online 2020 - Tried and True!

Do you like to stay active outdoors in spite of the freezing temperatures? Do you prefer to stay inside, but sometimes feel chilly? Or do you need a winter undershirt for wearing to the office? mybest is here to help you choose just what you're looking for!


Our editors searched Japanese e-commerce sites such as Amazon, Rakuten, and Kakaku.com for the best warm innerwear for men available online. We then picked out the most popular products and tested them.
We focused on 3 things:


  1. How well did it generate heat?
  2. How easily could we move around in it?
  3. Was the design good?


We then ranked the products and put what we learned into a buying guide to help you choose the best Japanese men's warm inner shirts available online.


  • Last updated: 01-09-2020
  • 69 views
Table of Contents

Top 14 Japanese Warm Inner Shirts for Men to Buy Online

Our editors searched Japanese e-commerce sites such as Amazon and Rakuten for the best heat-generating men's innerwear available online. We then picked out the most popular products and tested them.


In our evaluation, we focused on 3 things:


  1. How well it generated heat
  2. How easy it was to move around in
  3. How much we liked the design

We then ranked the products and put what we learned into a buying guide to help you choose the best Japanese warm shirts for men available online.

1

GunzeInnershirt Hot Magic Super Stretch

$19.08

JapaneseGUNZEインナーシャツ ホットマジック スーパーストレッチ Vネックロングスリーブ)
SizesM, L, LL
Materials30% nylon, 30% acrylic, 20% cupra, 15% polyester, 5% polyurethane, stretch deformed milled wool (lining)
Heat generationA+ (6.5℉)
Ease of movementB
DesignC
Overall gradeA
2

GunzeInnershirt YG Heat & Warm Series

$19.08

JapaneseGUNZEインナーシャツ YG Heat&WARMシリーズ Vネック 9分袖
SizesM, L, LL
Materials45% cotton, 25% acrylic, 20% rayon, 5% nylon, 5% polyurethane
Heat generationA (6℉)
Ease of movementA
DesignA+
Overall gradeA
3

UniqloHeattech Extra Warm

$24.90

JapaneseユニクロヒートテックエクストラウォームVネックT(9分袖・極暖)
SizesXS-4XL
Materials50% acrylic, 33% rayon, 13% polyester, 4% polyurethane
Heat generationA (+6℉)
Ease of movementA
DesignA
Overall gradeA
4

ShimamuraFiberheat Warm Inner

$9.00

Japaneseしまむら発熱インナー
SizesM-XL
MaterialsN/A
Heat generationA (+6℉)
Ease of movementA
DesignB
Overall gradeA
5

UniqloHeattech Ultra Warm Crew Neck Tee

$29.90

JapaneseユニクロヒートテックウルトラウォームクルーネックT(9分袖・超極暖)
SizesXS-4XL
Materials47% acrylic, 26% polyester, 20% rayon, 7% polyurethane
Heat generationA (+5.8℉)
Ease of movementC
DesignB
Overall gradeB
6

GunzeBody Wild Long-Sleeved Shirt V-Neck

$15.47

JapaneseBODY WILDロングスリーブシャツ Vネック
SizesM, L, LL
Materials55% acrylic, 40% nylon, 5% polyurethane
Heat generationC (+4℉)
Ease of movementA
DesignA+
Overall gradeB
7

ZOZOHEATZOZOHEAT Long-Sleeved Crew Neck

$9.00

JapaneseZOZOZOZOHEAT 長袖クルーネック
SizesCustom/Made to order
Materials48% acrylic, 44% rayon, 5% wool, 3% polyurethane
Heat generationA (+6℉)
Ease of movementA
DesignA+
Overall gradeB

Compare the Best Japanese Men's Warm Innerwear

Image
1
Gunze Innershirt Hot Magic Super Stretch 1

Gunze

2
Gunze Innershirt YG Heat & Warm Series 1

Gunze

3
Uniqlo Heattech Extra Warm 1

Uniqlo

4
Shimamura Fiberheat Warm Inner 1

Shimamura

5
Uniqlo Heattech Ultra Warm Crew Neck Tee 1

Uniqlo

6
Gunze Body Wild Long-Sleeved Shirt V-Neck 1

Gunze

7
ZOZOHEAT ZOZOHEAT Long-Sleeved Crew Neck 1

ZOZOHEAT

Name

Innershirt Hot Magic Super Stretch

Innershirt YG Heat & Warm Series

Heattech Extra Warm

Fiberheat Warm Inner

Heattech Ultra Warm Crew Neck Tee

Body Wild Long-Sleeved Shirt V-Neck

ZOZOHEAT Long-Sleeved Crew Neck

Featuresmybest's Top Choice! Our Fa...An All-around Great ShirtOur Favorite (and the Warme...The Best Inner Shirt for a ...The Best Inner Shirt for Lo...Recommended to Wear as an O...Recommended if You Want a C...
Price$19.08$19.08$24.90$9.00$29.90$15.47$9.00
JapaneseGUNZEインナーシャツ ホットマジック スーパーストレッチ Vネックロングスリーブ)GUNZEインナーシャツ YG Heat&WARMシリーズ Vネック 9分袖ユニクロヒートテックエクストラウォームVネックT(9分袖・極暖)しまむら発熱インナーユニクロヒートテックウルトラウォームクルーネックT(9分袖・超極暖)BODY WILDロングスリーブシャツ VネックZOZOZOZOHEAT 長袖クルーネック
SizesM, L, LLM, L, LLXS-4XLM-XLXS-4XLM, L, LLCustom/Made to order
Materials30% nylon, 30% acrylic, 20% cupra, 15% polyester, 5% polyurethane, stretch deformed milled wool (lining)45% cotton, 25% acrylic, 20% rayon, 5% nylon, 5% polyurethane 50% acrylic, 33% rayon, 13% polyester, 4% polyurethaneN/A47% acrylic, 26% polyester, 20% rayon, 7% polyurethane55% acrylic, 40% nylon, 5% polyurethane48% acrylic, 44% rayon, 5% wool, 3% polyurethane
Heat generationA+ (6.5℉)A (6℉)A (+6℉)A (+6℉)A (+5.8℉)C (+4℉)A (+6℉)
Ease of movementBAAACAA
DesignCA+ABBA+A+
Overall gradeAAAABBB
Link

Products That Didn't Make the Cut

And why they didn't quite make it.

GU's Warm V-Neck Tee is so thin that depending on the color, you may show off more of your body than you want others to see. The shoulders are roomy, but the arms are tight. At least it's elastic, so you can still move easily.

Uniqlo's Heattech V-Neck Tee produced less heat than the average. The fabric is lightweight and snug, so it's easy to move in, but if you exercise and sweat, you'll get cold. It seems more like an undershirt than something to keep you warm.

BROS Men's Innershirt by Wacoal has a weird striped pattern because of the texture of the fabric. It's black and charcoal gray, and too subtle to look like an intentional fashion statement. We would be embarrassed if someone saw it peeking out from our collar. It 's stretchy, but the arms are tight, so we also weren't impressed with the ease of movement.

Une Nana Cool Men's Inner Moisture Heat-Generating Brushed Fabric shirt is a thick fabric with a fluffy fleece lining. It feels warm, but doesn't generate heat well. It's not elastic either, but the fit is loose. The main thing we didn't like was the design- the round collar especially makes it look like underwear.

The Winter Use U-Neck Long-Sleeved Shirt by Seek (Isetan) looks fashionable, and we thought the wide neckline would be practical under certain shirts. But in reality, the wide neck means the chest is open and the fit is loose. The result is cold air can get in! So we don't think it's good as a "warm inner."

Mizuno's Outdoor Underwear didn't generate much heat in our tests. The fight is very snug, and seems designed for a slim guy. Bending your elbow makes it feel taught. We recommend ordering one size up if you have a wide chest or muscular upper body.

Shimamura's Fiberheat looks like pajamas. It's thick brushed material, but it's shiny on the outside. It's also loose-fitting and doesn't generate heat particularly well. You might wear it to bed if you like a roomy fit.

How We Tested the Innerwear

How We Tested the Innerwear

We put each product through 3 tests. 


  • How well did it generate heat?
  • Was it easy to move around in?
  • Was it a good design?


Then we ranked each shirt on a scale of A to D+.

Test ① How Well Did it Generate Heat?

Test ① How Well Did it Generate Heat?

Heating fabrics work by producing heat from the absorption of moisture. (This exothermic process is called hygroscopic heat generation, if you're interested in the science!) To test this functionality, we  enlisted the help of a specialized institution to measure the level of moisture absorption and exothermicity of the fabric of each product.


The fabric was placed in an environment where the humidity increased over time, and then the change in surface temperature was checked every 60 seconds. Fabric that had a larger temperature difference is better at moisture absorption and heat generation.

Test ① How Well Did it Generate Heat?

Our tests showed that despite all the science of synthetic fabrics, natural fibers have stronger heat-generating power. A blend of cotton and wool performed well. (Of course, synthetics have other advantages, so choose based on your needs.)

Test ② Was it Easy to Move Around In?

Test ② Was it Easy to Move Around In?

We wore the inner and moved around to check the overall fit and freedom of movement. We paid special attention to the shoulders and elbows.

Test ② Was it Easy to Move Around In?

We found that the structure and size influenced the freedom of movement most. Products designed to be used as undershirts were fitted to the body but didn't feel tight. On the other hand, they also weren't too loose, so they wouldn't get in the way of your outer shirt.

Test ③ Was it a Good Design?

Test ③ Was it a Good Design?

Last, we checked the design. How was the neckline, sleeve length, thickness and texture? Were the seams large or small? What about the color?  We really liked shirts that looked as if they could be worn by themselves and not hidden under another shirt.

Test ③ Was it a Good Design?

Our test proved that fabric can indeed be too thin. Some of the shirts were so transparent we wanted to wear another shirt underneath! 


We also found that flat collar ribs and seams which are inconspicuous are important to give a high-fashion feel and move a shirt from the realm of pajamas to daily wear. However, some of the shirts were overdesigned, which limited their versatility.

How to Choose a Warm Inner- Buying Guide

We have 3 tips for you to help you choose the right warm inner for your needs.

① Choose Innerwear That Has Good Hygroscopic Properties

① Choose Innerwear That Has Good Hygroscopic Properties

When you sweat, your body cools down. If you sweat in a cold environment, your body could lose heat rapidly. But if you are wearing hygroscopic exothermic fabric, sweating will generate heat and you'll stay warm. And if you move from a warm room to the cold outdoors, a good shirt should keep your body at the same stable temperature.


Natural material like cotton, wool, and silk are highly hygroscopic. Wool is particularly good, but many people don't like the itchiness. So, wool is often blended with cotton for undergarments.


Synthetic fibers are generally less hygroscopic than natural fabrics. To improve their functionality, they are often blended with acrylate fibers, so look for that term on the label.

② Choose a Material That Matches Your Lifestyle

② Choose a Material That Matches Your Lifestyle

Speaking of fabrics, you shouldn't just choose one that is the top-seller, because your needs may be different. Depending on the material, the functionality, texture, and care requirements will vary. Below, we've summarized the properties of different materials for you.

Natural Fibers

Natural Fibers
  • Cotton

Cotton feels nice on the skin, has good hygroscopic properties, and is durable. It can be machine-washed. But, it wrinkles easily and dries slowly.


  • Silk

Silk feels cool in summer and warm in winter! It's pliable and resistant to static electricity. But it doesn't hold up under a lot of friction, and it can't be washed in the washer. It also gets discolored by sunlight and moths love to eat it.


  • Wool

Wool has excellent heat retention and elasticity. It doesn't feel tight, but it can shrink when washing and drying (never dry it in the dryer!) It's also thick, and bugs will eat this, too.

Synthetic Fibers

Synthetic Fibers
  • Polyester

Polyester is durable, elastic, and wrinkle-resistant. It doesn't absorb moisture easily and dries fast. But it's prone to getting dirty and attracting static electricity.


  • Rayon

Rayon has great heat retention and elasticity. It's soft and comfortable, but wrinkles easily and is not machine washable.


  • Acrylic Fibers

Acrylic fibers are mold-resistant, hold heat well, and are elastic. But they attract static electricity, can change color when exposed to sunlight, and can melt under extreme heat.

③ Choose a Design You Like

③ Choose a Design You Like

You may want to buy a shirt just for use under another shirt, and think design isn't important. But what if you go into a room that's too hot? If your inner is ugly, you'll be embarrassed to unbutton your collar or roll up your sleeves.


When considering the design, check the thickness of the material and the neck and cuff seams. Be careful about items that are see-through, are too glossy or shiny, or have ribbing that looks like underwear. For use under a work shirt, we recommend a neutral beige that matches your skin.

Looking for More Ways to Enjoy the Winter Season? Check Out These Related Links!

Looking for More Ways to Enjoy the Winter Season? Check Out These Related Links!

Now that you're all warm and toasty, it's time to get out there and enjoy! Or you could stay in.

Summary

mybest looked at 14 of the most popular Japanese men's warm inners available online and tested them all. We found that natural fibers performed very well. Just because something has a powerful-sounding name doesn't prove it's better! Those names are just trademarks and the materials are often the same polyester as another company.


Author: Sayako Suzuki/Translation: Susan Lucier-Ogawa/Photos: Koichi Miura

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