Behind the Scenes: The Story Behind Wacoal's "Sweat-Wicking and Quick-Drying Synchro Bra Top"

The "Synchro Bra Top" series, from Wacoal Corp.'s Wing brand, has shipped over 2 million units cumulatively since April 2019 (from April 2019 to December 2025).

It was designed without an under-bust elastic in response to customers wanting a comfortable fit with less constriction. But how is it possible to also deliver a beautiful silhouette comparable to a bra and pack in numerous features to survive the harsh summer?

In this article, we spoke with Asami Matsuo of the Wing brand's Product Planning Division about the story behind the development of the sweat-wicking, quick-drying model in the "Synchro Bra Top" series. We'll reveal where underwear manufacturers stand today in their challenge to design comfortable innerwear.

Balancing the Conflicting Needs of "Comfort" and "Beauty"

Around 2018, as demand for non-wire bras grew, lingerie options were becoming more diverse. A survey conducted by Wacoal revealed a common complaint from bra top users: \"By evening, the under-bust elastic digs in and feels tight around my stomach.\" Some had even stopped wearing bra tops altogether due to this discomfort. Addressing this issue became the starting point for the development of the "Synchro Bra Top" in 2019.

The development team was fully committed to creating a less restrictive bra top, but they encountered unexpected feedback early on. When they designed a looser-fitting prototype to reduce constriction, complaints like, \"I'm afraid it will ride up,\" and, \"It doesn't feel like it fits properly,\" emerged. This was especially true for users with larger cup sizes.

\"If 'easy to wear' was the only concern, a simple undershirt with round pads would do the trick,\" Matsuo reflects. \"However, we realized there was a deeper need; people weren't choosing them just to cover their bust. We knew we had to deliver a product that felt secure and fit well without being uncomfortably tight.\"

How to integrate these conflicting elements—a fit that is less restrictive yet secure, while also creating a beautiful silhouette—became the most time-consuming challenge for the development team.

The Perfect "Sweat-Wicking and Quick-Drying" Solution for Sweaty Seasons

The quest for a comfortable feel naturally led to selecting materials suitable for different seasons and environments. The "sweat-wicking and quick-drying" version of the Synchro Bra Top was the second model released, following the cotton-blend type, and was specifically designed for sweaty summer conditions. It passed internal tests for light exercise and boasts functionality that makes it recommended for activities like yoga and walking.

To address complaints about the previous sweat-wicking model—that it would "stick and feel clammy with sweat"—the team used a breathable mesh for the lining. This wasn't just about improving airflow. They carefully selected the final fabric from six to eight candidates, seeking a balance to ensure the mesh's texture wouldn't catch on the skin even when damp. Additionally, they added a cool-to-the-touch feature to the lining, the part that makes the most contact with the skin during changing, to help ease the discomfort of summer heat.

Conversely, for the outer fabric, the team chose a fine, flat-weave knit known as "Tenjiku" (jersey stitch).

"For the exterior, we wanted a clean finish that didn't look like typical underwear, so we chose a fine-gauge Tenjiku knit," she says. "Fabric being see-through can make people feel self-conscious, so we focused heavily on developing a material that was thin but also opaque."

While pursuing high functionality, the design doesn't compromise on its "appearance as apparel," whether it's peeking out from under a shirt or worn with a T-shirt layered over it. This focus on fitting into a woman's daily life and maintaining its beauty as a piece of clothing is evident in every aspect of the material selection.

A Silhouette and Fit Born from Millimeter-Scale Adjustments

Beyond its choice of materials, a precision pattern was engineered to resolve common structural complaints with bra tops. Many products on the market use separate left and right cups, which has a tendency to let the bust spread outwards as the surrounding fabric stretches. Wacoal’s solution was to use a single, integrated molded cup, with added thickness at the bottom to create a natural lift and centered shape.

Furthermore, to tackle the problem of the top edge gaping away from the body, the design team completely re-evaluated the angle from the bust point to the top line. For the full size range from S to 4L(*), they worked with fitting models of every size to test and perfect the optimal lift and fit for a variety of bust shapes.

"If the angle from the bust point to the top edge is too wide, it can cause gaping. Our pattern team made countless millimeter-scale adjustments to engineer the ideal angle for every single size."

*Sizing may vary by color.

In addition to the cup design, which underwent a year of repeated, millimeter-level refinements, clever details were added to reduce pressure on the stomach area. The bra top features a free-cutting design with no under-bust elastic, and the band is shaped into a gentle curve instead of a straight line. This kind of insight, which could only come from a manufacturer with an intimate knowledge of bra construction, provides beautiful and comfortable support for the entire silhouette from cup to band.

This innovative design is backed by Wacoal's own rigorous quality standards. Despite its free-cutting construction, special attention was paid to wash durability through a careful selection of materials and cup structures. Leveraging long-standing relationships built on trust with engineers and material suppliers, Wacoal achieves a high standard of quality in both comfort and functionality.

A Lingerie Maker's Dedication: The Vision for the Future

The Synchro Bra Top series, which masterfully blends "comfort" and "beauty," has shipped over 2 million units between April 2019 and December 2025. Today, the lineup has expanded to meet diverse needs with cotton-blend, sweat-wicking, ribbed, and slim-strap versions. The company is now aiming to sell 1.1 million units annually by 2026.

To make finding the right size easy, Wacoal offers two sizing methods: one based on your usual bra size and another based on your top bust measurement. This thoughtful detail is designed to cater to each person's unique body shape.

Matsuo shares her passion: "'The bra top seriously made by a lingerie maker'—just as our tagline says, I feel that what customers value most is the fact that it's a Wacoal product. As a bra manufacturer, we will continue to develop products that live up to that name, delivering a bust silhouette and fit we can be proud of."

Wacoal is channeling its vast data and technical expertise—cultivated over decades of studying the female form—into the new frontier of bra tops. The company is poised to continue setting new benchmarks for comfort in the innerwear market, with plans that include developing new, highly breathable models to help wearers beat the summer heat.