With summer just around the corner, it's the season for casual items like T-shirts, shorts, and sandals. However, as we get older, many people worry that they might look too casual and sloppy.
For this "Adult Field Trip," GUIDE crew members Tsuchiya, Okada, and Tashiro visited the men's tailored clothing section on the 5th floor Isetan Shinjuku Store, Men's Building . They were given suggestions for sophisticated summer short-sleeved outfits that even adults can pull off.

Pitfalls of summer casual wear and key points for adult short-sleeved outfits

"When the temperature rises, we tend to stick to casual wear like T-shirts, shorts, and sandals," the crew members said.

Styles that worked well in your 20s might seem "too casual" once you reach your 30s. This time, with the theme of "short-sleeved styles that balance comfort and sophistication," Iwata, assistant buyer for men's tailored clothing on the 5th floor Isetan Shinjuku Store, Men's Building will give a lecture on the perfect outfits for each of the three.

Tsuchiya: "A white T-shirt paired with navy slacks creates a simple yet elegant look."

Iwata suggested to Tsuchiya an outfit centered around a basic white T-shirt.
"Everyone tries on a white T-shirt at least once, but because it's so simple, there's no room for error, making it surprisingly difficult to pull off," says Iwata, recommending a white T-shirt from SUNSPEL that highlights the quality of its premium material.


The clay is incredibly soft and smooth. I feel like I can tell the difference the moment I hold it in my hand.

Iwata SUNSPEL 's T-shirts have a refined look with thin ribbing around the neckline, and the silhouette is well-designed, incorporating many details that give them a mature appearance.


For the bottoms, I selected navy slacks from +CLOTHET that offer a polished yet relaxed feel. They have an elastic waistband, creases, and a beautiful silhouette.


Iwata Cross Closet is a brand originating from a textile trading company, and it is committed to high-quality materials and stitching. Even a simple combination of a white T-shirt and navy slacks can look sophisticated and refined by choosing high-quality materials and exquisite silhouettes.

These Tsuchiya pants look smart, but they're incredibly comfortable to wear. The smooth material and the bluish-navy color give them a summery and refreshing feel.

Okada: "Earth tones x linen create a cool, sophisticated look for adults."

Iwata suggested to Okada that "the key to summer T-shirt styles, which tend to be casual, is to create a more mature look with the right material and color," and recommended a linen T-shirt from Cross Closet. The outfit made the most of the natural earth tones and linen material.


The crispness unique to Okada linen feels great. It doesn't cling to the skin, so I think I could stay comfortable even in the middle of summer. The colors are also subdued and seem easy to coordinate.

Iwata linen is highly breathable and dries quickly even when you sweat, making it truly ideal for summer. The earth tones give it a sophisticated look without being too casual. I think mature men, in particular, should embrace these natural color palettes.

For bottoms, I chose cotton trousers from the Japanese tailor brand FUMIYA HIRANO THE TROUSERS. They feature side adjusters, making them a great choice for a neat, beltless fit.


These pants by Okada have a really nice silhouette. The side adjusters make the waist area look neat, and they would look great tucked in.


Iwata Fumiya Hirano THE TROUSERS is a brand renowned for its tailoring, so even their casual cotton pants stand out for their excellent craftsmanship. Even a simple combination of a T-shirt and pants takes on a refined look thanks to these attention to detail.

Tashiro: "A short-sleeved set-up creates a sophisticated and distinctive look for a 'new summer'."

For Tashiro, we suggested a coordinated outfit featuring a seemingly niche combination of "short sleeves x matching suit."


"Summer suits can often feel stiff, but choosing short sleeves and lightweight materials instantly creates a fresh impression. It also gives off a relaxed, grown-up vibe," says Iwata, recommending a wool woven suit from JOHN SMEDLEY .

I always associated John Smedley with knitwear, but I didn't know they also made sets in woven fabrics like this. The dark navy color is nice and not too heavy.


When Tashiro actually tried it on, she praised it, saying, "It's even more comfortable than I imagined," and it also stood out for its sophisticated, mature look.

Iwata's fit is just right—not too loose, but not too loose either. The pants also have no seams on the sides, giving them a clean, relaxed feel while still looking elegant.


The excellent tailoring of the white fabric makes it cool and easy to move in. For footwear, loafers or white leather shoes are good choices, and you can add a touch of style with accessories like a neckerchief.

Enjoy a sophisticated summer with the right texture, color, and silhouette.

As Iwata showed us, even summer short-sleeved outfits can look sophisticated and grown-up if you pay attention to the materials, colors, and silhouettes, rather than being too casual. White T-shirts and slacks, linen T-shirts and cotton pants, short-sleeved sets—all of these styles strike a balance between comfort and a polished look.


At the Isetan Shinjuku Store, Men's Building 5th floor, pop-up shops and promotions by this season's hottest brands, such as SUNSPEL and Cross Closet, will be held one after another. Be sure to visit the shop this summer to experience elegant and cool "short-sleeved adult outfits."

Watch the full video here ► Summer short-sleeved outfits for adults to enjoy