2026.05.27 update

For managing sweat under your trousers in the summer, we recommend wearing long pants! Three users share their thoughts on the best summer underwear choices for men. [Updated May 2026]

Porter Classic Hawaiian Love 2026
Have you ever experienced the discomfort of sweating around your waist, buttocks, or the backs of your thighs when wearing pants? Especially during the summer months when you tend to sweat more, many men are bothered by noticeable sweat stains on their pants, as well as the dampness and odor in the crotch area.

To stay comfortable in pants during the summer, we recommend wearing long pants.
Modern long pants have evolved to a level of functionality far superior to the "long underwear" or "underpants" worn by our fathers' generation. They not only prevent stickiness caused by sweat, but also protect the fabric, are less see-through, and maintain a flattering silhouette, demonstrating their unique continuous advancements.

This time, we held a roundtable discussion with three Mitsukoshi Isetan employees who have strong opinions on "long pants." We asked them why they continue to wear long pants.

The three individuals who participated in this "Ronpan" roundtable discussion * (organizations and roles are based on information as of July 2021) are listed below.
Yasuhiro Ohashi
Isetan Shinjuku Store, Men's Building , B1F, Men's Underwear Buyer
 
Keita Tashiro
Mitsukoshi Isetan Web Media & E-commerce Director
 
Yuki Masuda
Isetan Shinjuku Store, Men's Building , B1F, Men's Underwear, Assistant Buyer
 

View the "Summer Long Pants" product list at the Mitsukoshi Isetan Online Store.



  1. The reason we started wearing "long pants"
    1. I was troubled by the discomfort caused by sweat and sweat stains on my pants.
    2. My experience wearing "long pants" under my trousers as a way to combat summer sweat.
  2. Four recommended long pants for summer that you won't want to take off once you try them.
    1. 1. These long pants are perfect for those who want something that won't show through their trousers and also helps with odor control! SEEK knee-length/front-opening "EE3406A"
    2. 2. The soft elastic waistband and mesh material make them comfortable to wear! SEEK Knee-Length/Front Opening "EE3688A"
    3. 3. An excellent product that is 100% cotton yet also has cooling and quick-drying properties. SEEK Half Pants / Front Opening / Knee-Length "EE1007C"
  3. In conclusion, when it comes to dealing with sweat on your buttocks, the backs of your thighs, and the backs of your knees in the summer, paying attention to your innerwear will allow you to enjoy fashion even more!
 

The reason we started wearing "long pants"

I was troubled by the discomfort caused by sweat and sweat stains on my pants.


Tashiro:
Today we'll be discussing long pants, and I'd say about half of the employees at Isetan Shinjuku Store, Men's Building wear them now. What kind of comments do you often get from customers who come to the underwear floor to buy these long pants?

For those who want to prevent their underwear from showing through when wearing light -colored pants, and also for those who want to alleviate lower body sweat problems with innerwear during the summer months, this product is for you.
Some people sweat from their waist, buttocks, the backs of their thighs, and behind their knees, and want to solve the problem of sweat stains on their pants, or the discomfort caused by dampness in the crotch area.

Many customers choose knee-length pants, but if you're going to wear them, we recommend knee-length pants that cover up to the back of your knees, allowing you to experience the full benefits of long pants.

As summers get hotter every year, suits and trousers made with functional materials like cooling fabrics have become commonplace. However, I believe that wearing a suit made of natural materials like wool, paired with highly functional innerwear that addresses common concerns, will allow you to stay stylish, comfortable, and confident.



My experience wearing "long pants" under my trousers as a way to combat summer sweat.


Masuda: I started working on men's underwear last year, and during the height of summer, I wore SEEK 's "mesh knee-length boxer shorts." Even when wearing them under sweatpants on my days off, I didn't feel any discomfort from sweat, and I was able to move around comfortably all day long feeling refreshed. The effect was better than I expected, even though I was only wearing one layer of underwear.

Tashiro: Previously, when I was working in a store, I had to bend my knees and move around a lot, so I would sweat easily behind my knees, and sweat stains would appear on the fabric of my pants... I didn't like the fabric of my pants getting damaged, so I started wearing long pants as a way to deal with the sweat. At first, I wore them over boxer shorts, but one day I tried wearing long pants directly without underwear, or "pants off," and I was surprised at how comfortable and pleasant it was.

Ohashi:
Regarding this "wearing or not wearing underwear" issue, which side are you on, Masuda-san?

I wore underwear with Masuda SEEK 's slightly looser, knee-length style, but when I wear SEEK 's "knee-length" style, which has a stronger hold, I also go without pants.
Like Mr. Tashiro, I also suffer from excessive knee sweating at the back of my knees due to frequent bending and straightening of my knees at work. However, wearing these long pants eliminates that problem. Since sweat doesn't directly touch the fabric, it also prevents sweat stains. Personally, I feel that the biggest benefit is being able to wear my pants neatly and crisp for extended periods.

Ohashi and SEEK also offer a unique style that doesn't have an elastic waistband. Removing the elastic eliminates the feeling of tightness around the waist, making it even more comfortable for summer!

Porter Classic Super Nylon Tote Bag
Tashiro: I prefer the quick-drying type. I like its quick-drying properties, which help with recovery from sweat on my buttocks and behind my knees. By the way, Ohashi, would you also consider "panty-free" underwear? (laughs)

Ohashi: For me, on scorching hot days when the temperature exceeds 35 degrees Celsius, I take a "pan-off"! (laughs)
The four types of long pants we're introducing today differ in silhouette and length, but all of them stand out among our underwear products for their "moisture-wicking and quick-drying" properties, which allow them to quickly absorb and dry sweat. We hope you find the perfect pair of long pants for this summer that suits your style.


Four recommended long pants for summer that you won't want to take off once you try them.


1. These long pants are perfect for those who want something that won't show through their trousers and also helps with odor control!
SEEK knee-length/front-opening "EE3406A"



Porter Classic Super Nylon Helmet Case S seek
Knee-length/front-opening "EE3406A" ¥3,630

View Products

 

Closeness ★★★☆☆
Functionality ★★★☆☆
Impact on underwear: ★★★★☆
Comfort Index ★★★★☆
Style rating: ★☆☆☆☆

[Features] SEEK knee-length pants. The front opening uses highly twisted yarn for a crisp feel against the skin. The leg openings have a raw edge finish, making it less likely for underwear to show through pants. It has an effect of suppressing odor caused by sweat, etc. It also has deodorizing and antibacterial properties.

Porter Classic Super Nylon Helmet Case Mini
Porter Classic Super Nylon Simple Shoulder Bag Mini

I mainly do desk work now, but the office is surprisingly hot, and when I sit and work for long periods, I really notice that my bottom gets sweaty and the backs of my knees become damp. When I wear these long pants, they reach below my knees, so I don't have to worry about sweating. I also love that they look stylish even under slim-fit tapered pants and don't feel bulky or stiff. (Tashiro)

View the "Summer Long Pants" product list at the Mitsukoshi Isetan Online Store.




2. The soft elastic waistband and mesh material make them comfortable to wear!
SEEK Knee-Length/Front Opening "EE3688A"


seek
Knee-length/front-opening "EE3688A" ¥3,960

View Products

 

Closeness ★★★★★
Functionality ★★★★★
Impact on underwear: ★★★☆☆
Comfort Index ★★★★★
Style rating: ★★☆☆☆

【Features】 SEEK 's "Knee-Length Front Opening" pants feature a mesh material for a comfortable, dry feel. The waistband uses a soft material. It offers excellent breathability, absorbing and wicking away sweat to reduce stuffiness.



The best thing about this product is definitely the soft, stretchy knit elastic waistband. It's comfortable to wear without leaving any marks. It feels like slightly fitted shorts, and in the summer, you can even wear it as pajamas while sleeping – it's very comfortable. (Masuda)

View the "Summer Long Pants" product list at the Mitsukoshi Isetan Online Store.



 

3. An excellent product that is 100% cotton yet also has cooling and quick-drying properties.
SEEK Half Pants / Front Opening / Knee-Length "EE1007C"



seek
Half-length shorts / front opening / knee-length (EE1007C) ¥3,850

View Products

 

Closeness: ★★★☆☆
Functionality ★★★★☆
Impact on underwear: ★★★☆☆
Comfort Index ★★★★☆
Style rating: ★★☆☆☆

[Features] Made with IC Cotton, a functional material that is 100% cotton yet combines a cool, refreshing feel with quick-drying properties that wick away sweat quickly.


Some people may have the impression that cotton is "stuffy," but this product is highly recommended for those people. In addition to the comfortable feel of 100% cotton, it also has cooling and quick-drying functions, making it a great product that feels cool against the skin and is less prone to stuffiness.
The fabric is thin and the silhouette is slim, so it won't show through your pants. It's also recommended as an inner layer for those who are sensitive to synthetic fibers, and it's a popular item with many repeat customers at Isetan Shinjuku Store, Men's Building . (Masuda)

View the "Summer Long Pants" product list at the Mitsukoshi Isetan Online Store.



In conclusion, when it comes to dealing with sweat on your buttocks, the backs of your thighs, and the backs of your knees in the summer, paying attention to your innerwear will allow you to enjoy fashion even more!


Masuda:
I find it cooler to wear loose long pants under slim-fitting pants, and I feel more comfortable wearing fitted long pants with loose-fitting wide-leg pants.

Ohashi : I see. I wear fitted long pants for slimmer people and loose long pants for looser people, but I guess there are also people like Masuda-san.

Tashiro: It's a good idea to have a few pairs of long pants from the three types we introduced today that suit you, and wear them according to your outfit.
For those who want to wear denim in the summer but are worried about it being too hot, stuffy, and showing sweat stains, I highly recommend long pants. If you're going to outdoor events like summer festivals, BBQs, or fireworks displays, I definitely recommend wearing long pants under your trousers. It will solve the discomfort that comes with sweating in the summer.

If you choose three items to mix and match for a week, it will cost you about 10,000 yen for the summer, but I would like you to experience at least once the feeling of "sweating but not feeling like you're sweating."

As someone in my mid -30s, I'm still from a generation that's a bit hesitant about wearing long underwear, but when I recommend it to my friends and they try it once, they all say they can't live without it! It's a huge difference compared to just wearing long pants.

Once the rainy season ends in Ohashi , the real heat will finally arrive. We highly recommend trying Longpan to stay comfortable during the peak of summer.
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*All prices include tax.
*The information in this article is current as of the time of publication. Product information may be revised or changed without notice.

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