• Top 13 Best Japanese Women's Warm Innerwear to Buy Online 2020 - Tried and True! 1
  • Top 13 Best Japanese Women's Warm Innerwear to Buy Online 2020 - Tried and True! 2
  • Top 13 Best Japanese Women's Warm Innerwear to Buy Online 2020 - Tried and True! 3
  • Top 13 Best Japanese Women's Warm Innerwear to Buy Online 2020 - Tried and True! 4
  • Top 13 Best Japanese Women's Warm Innerwear to Buy Online 2020 - Tried and True! 5

Top 13 Best Japanese Women's Warm Innerwear to Buy Online 2020 - Tried and True!

Brrrrrrrrr! It's freezing! I wish I had a super-warm, comfortable shirt that wasn't bulky to keep me nice and toasty in winter... mybest is here to help!


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


  1. How well did it generate heat?
  2. How comfortable was 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 warm inners available online.


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

Top 13 Japanese Warm Inner Shirts to Buy Online

We picked out some of the most popular products and tested them for heat generation, comfort, and design.

Then, based on our tests, we ranked the top 13 Japanese warm inner shirts available online.

Japanese prices for some of the products are given, but they've been converted into US dollars to make it easy for you.

1

GunzeInner Shirt Hot Magic

$35.50

JapaneseGUNZEインナーシャツ ホットマジック 極-kiwami- 8分袖
SizesM-XL
Materials55% acrylic, 20% synthetic fiber (acrylate fiber), 20% nylon, 5% polyurethane
Heat GenerationA+ (+7.2℉)
ComfortA+
DesignC
Overall GradeA+
2

ItoyokadoSeven Premium Lifestyle Body Heater

$14.20

Japaneseイトーヨーカドーセブンプレミアムライフスタイル ボディヒーター 婦人 厚地長袖シャツ
SizesS-3L
Materials33% acrylic, 31% rayon, 18% nylon, 17% cotton, 1% polyurethane
Heat GenerationA+ (+6.8℉)
ComfortA+
DesignC
Overall GradeA+
3

UniqloHeattech Extra Warm

$19.90

JapaneseユニクロヒートテックエクストラウォームUネックT(8分袖・極暖)
SizesXS-3XL
Materials46% rayon, 30% acrylic, 19% polyester, 5% polyurethane
Heat GenerationA (+5℉)
ComfortA+
DesignC
Overall GradeA
4

MujiCotton and Wool Warm Midwinter

$18.30

Japanese無印良品綿とウールで真冬もあったかUネック八分袖Tシャツ
SizesXS-XL
MaterialsCotton 90%, Wool 10%
Heat GenerationA+ (7.2℉)
ComfortC
DesignC
Overall GradeA
5

WacoalAmazing Clothing Natural Material Plus Knit Top

$39.10

Japaneseワコールスゴ衣 天然素材プラス やわらか、ひびきにくい ニットトップ スタンダードUネック
SizesM, L
Materials90% cotton, 10% polyurethane
Heat GenerationB (3.8℉)
ComfortA
DesignA
Overall GradeA

Compare the Best Japanese Women's Warm Innerwear

Image
1
Gunze Inner Shirt Hot Magic 1

Gunze

2
Itoyokado Seven Premium Lifestyle Body Heater 1

Itoyokado

3
Uniqlo Heattech Extra Warm 1

Uniqlo

4
Muji Cotton and Wool Warm Midwinter 1

Muji

5
Wacoal Amazing Clothing Natural Material Plus Knit Top 1

Wacoal

Name

Inner Shirt Hot Magic

Seven Premium Lifestyle Body Heater

Heattech Extra Warm

Cotton and Wool Warm Midwinter

Amazing Clothing Natural Material Plus Knit Top

Featuresmybest's Top Choice! Comfor...Perfectly Warm, Thick, and ...Recommended for Moderate an...Recommended if You Want Nat...So Thin, You Can Wear it Li...
Price$35.50$14.20$19.90$18.30$39.10
JapaneseGUNZEインナーシャツ ホットマジック 極-kiwami- 8分袖イトーヨーカドーセブンプレミアムライフスタイル ボディヒーター 婦人 厚地長袖シャツユニクロヒートテックエクストラウォームUネックT(8分袖・極暖)無印良品綿とウールで真冬もあったかUネック八分袖Tシャツワコールスゴ衣 天然素材プラス やわらか、ひびきにくい ニットトップ スタンダードUネック
SizesM-XLS-3LXS-3XLXS-XLM, L
Materials55% acrylic, 20% synthetic fiber (acrylate fiber), 20% nylon, 5% polyurethane33% acrylic, 31% rayon, 18% nylon, 17% cotton, 1% polyurethane 46% rayon, 30% acrylic, 19% polyester, 5% polyurethaneCotton 90%, Wool 10%90% cotton, 10% polyurethane
Heat GenerationA+ (+7.2℉)A+ (+6.8℉)A (+5℉)A+ (7.2℉)B (3.8℉)
ComfortA+A+A+CA
DesignCCCCA
Overall GradeA+A+AAA
Link

Products That Didn't Make the Cut

And why they didn't quite make it.

It's Hottie Furry by PeachJohn has sweat absorption pads in the armpits to prevent stains and wetness from showing. But they're kind of stiff and irritating. The wide collar is good for being invisible under other tops, but bad for showing bra straps. It's moderately warm.

Wacoal's Amazing Clothing Comfort Plus is a really stylish design, with a lace front collar that we want to show off by letting it peek out from under our blouse. Unfortunately, it didn't generate heat at all, so we'd call it just a regular undershirt. But it's smooth and soft.

GU's Form U-Neck Tee is stiff and doesn't stretch. The seams are large enough to create a gap on the sides, although the neck seams are less noticeable. Still, we didn't like how the fabric felt kind of tingly.

Uniqlo's regular Heattech line is probably the most well-known heat generating inner, but it actually didn't prove it was worthy of top-tier status. The thin fabric and open neck mean it lets cool air in. However, it fits well, and the material feels nice on the skin.

Innershirt KireiLabo by Gunze is thick, with a fleece back and small neck opening. So in that sense, it was warm. But we found that the heat generating properties were very low.

Shimamura's Thick-Lined Warm Inner is stretchy and comfortable. The brushed fleece material is warm, but it doesn't generate heat so well. It would be good for wearing under a sweater.

The other product we tested from Shimamura, the Brushed-Fleece Back Inner, is tight like a wetsuit and holds your body temperature to protect from cold. However, it doesn't produce much heat, so if you sweat it may chill you. The wide neckline may not hide your bra straps.

Breath Thermo Every Plus from Mizuno was uncomfortable, not particularly warm, and expensive because of the exclusive technology used to produce it. But most of all, the color, fit, and design combined to make us look frumpy.

How We Tested the Shirts

We put each product through 3 tests. The products were then given grades from 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 both synthetic materials AND natural materials can generate heat well. The highest-performing shirts were one with a 20% acrylate fiber blend, and another with a cotton/wool blend.

Test ② Was it Comfortable?

Test ② Was it Comfortable?

Our testers wore the shirts and rated them for how they felt and whether or not they were warm. We looked for fabrics that were not stiff or itchy. We also gave lower rating to ones that were too thin or felt cool to the touch. Our results showed that brushed, fleecy inners were the warmest and most comfortable.

Test ② Was it Comfortable?

This type of material feels warm as soon as you put it on. It's soft, too. We didn't notice a consistent difference in comfort between natural and synthetic fabrics; some of the natural materials felt itchy, and some of the synthetics were uncomfortable.

Test ③ Was it a Good Design?

Test ③ Was it a Good Design?

We checked the size and cut of the collar, the sleeve length, and the color and texture of the fabric. We also looked at how the seams were sewn. The highest scores went to products that look nice enough to wear as outer shirts, or showing partially under another shirt like an unbuttoned flannel.

Test ③ Was it a Good Design?

We gave low marks to shirts that were so thin they were see-through. We also were unimpressed with necklines that left our bra straps exposed. Heavier weight fabrics and deep V-necks scored better.

How to Choose a Warm Inner - Buying Guide

We have a few tips to help you choose the best warm innerwear.

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.

② Find a Material That Retains Heat and Has a Nice Texture

② Find a Material That Retains Heat and Has a Nice Texture

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.

③ Go with Something That Looks Good, Even if You Just Cover it Up

③ Go with Something That Looks Good, Even if You Just Cover it Up

Even if you plan to use it only as an undershirt, there may be times when it shows. What if it peeks out from your sleeve during a job interview, and it looks like grandma pajamas?! 


Even if you're not so fashion-conscious, a nice design can be worn as a shirt by itself, so it's more versatile. Consider the neckline, sleeves, hems, seams, color and texture.

Here Are Some More Tips to Stay Warm This Winter!

To keep your body warm from the inside, try to:


  • Eat foods that are warm. Root vegetables like ginger, carrots, and onions, and spicy vegetables such as leeks, garlic and chilis are known for their ability to raise the body's temperature. Of course, hot drinks and soup are great, too.

  • Improve your circulation and raise metabolism. Soaking in a hot bath, getting exercise, and avoiding strict diets are good ways to keep your muscles warm.

Looking for More Ways to Survive the Cold Weather? Check Out These Related Links!

Looking for More Ways to Survive the Cold Weather? Check Out These Related Links!

You'll need a lot more than good innerwear to stay comfortable during the cold winter months. Here are some other great products to help you survive!

Summary

mybest looked at 13 of the most popular Japanese warm inners available online and tested them all. We found that natural fabrics felt like quality items, but synthetics absorbed moisture better, generated heat efficiently, and were generally warmer.

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

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