Sacai x Birkenstock: Chitose Abe Rebuilds the Summer Sandal

On June 28, 2026, near the end of Paris Men’s Fashion Week, Chitose Abe did not simply update a summer sandal. She rebuilt it. The new BIRKENSTOCK x sacai collaboration, unveiled during sacai’s Spring/Summer 2027 men’s collection, introduces two silhouettes: the Aoyama 107 and the Cassette 75. Neither is a routine colorway. Both are acts of reconstruction, taking Birkenstock’s historic forms apart and putting them back together through sacai’s hybrid design language.

At first glance, this is an anticipated Spring 2027 footwear release. Pull back, and the story becomes bigger. German footbed culture, Japanese hybrid construction, Paris runway theater, Tokyo’s Aoyama district, and Rue Cassette in Saint-Germain-des-Prés are all folded into one pair of sandals. A single shoe carries more than half a century of footwear history and more than 25 years of sacai’s design philosophy.

What was unveiled: Aoyama 107 and Cassette 75

According to Birkenstock’s official announcement, the collaboration centers on three key Birkenstock models. The first is the brand’s original footbed sandal from 1963, later known as the Madrid, with its single strap. The second is the Arizona, the two-strap sandal launched in 1973. The third is the Boston clog, introduced in 1976.

The Aoyama 107 connects the Madrid’s one-strap identity with the Arizona’s structure. Its name references sacai’s iconic Tokyo store in the sophisticated Aoyama district. The Cassette 75 combines Arizona strap language with Boston clog volume; its name refers to sacai’s Paris headquarters on Rue Cassette in Saint-Germain-des-Prés.

The materials are premium natural and suede leathers, centered on Birkenstock’s cork-latex footbed wrapped in leather. The palette is black and taupe. The shoes remain recognizably Birkenstock, but the proportions, straps, closures, and outlines have shifted. Abe has not covered a classic with surface novelty. She has moved the structure inside the classic.

Why sandals matter

In fashion, a dress or jacket can carry drama more easily. A sandal is harder. It is too close to ordinary life: the doorway, the trip, the dog walk, the grocery store, the airport, the summer commute, the hotel corridor. A sandal enters the wearer’s life in a way runway pieces rarely do.

That is why redesigning a sandal is difficult. Push too far and it stops being useful. Hold back too much and it becomes a minor color update. Birkenstock’s strength has always been its commitment to walking, support, and the shape of the foot. Sacai’s strength is its ability to read the structure of familiar clothes and objects, then shift the boundary lines.

The Aoyama 107 and Cassette 75 bring those strengths together. Madrid, Arizona, and Boston are tools of daily life. sacai turns them into design propositions. Function and fashion, everyday use and runway thinking, German footbed engineering and Tokyo construction share the same sole.

Birkenstock history: from health shoe to fashion center

Birkenstock’s appeal began with structure more than glamour: the footbed, support, walking, posture. The 1963 Madrid was healthy, unisex, minimal, and almost defiantly plain compared with the shoe fashions of its time. Birkenstock’s official history describes it as the original Birkenstock footbed sandal, placed on the market in 1963 and later sold under the name Madrid.

In 1973 came the Arizona, the two-strap sandal that would become one of the most recognizable Birkenstock shapes in the world. In 1976 came the Boston clog, a closed-toe form that moved between house shoe, work shoe, street shoe, and fashion object.

For decades, Birkenstock lived on the border between style and utility: healthy, sturdy, a little ungainly, but difficult to give up. From the 1990s onward, fashion kept rediscovering that awkward honesty. Normcore, dad style, ugly shoes, outdoor dressing, wellness, relaxed luxury — each era found a new reason to need Birkenstock.

From the 2010s, Birkenstock also moved closer to luxury fashion through runway moments and collaborations. The brand’s plainness became a kind of authority. It was not a shoe trying to become fashionable. It was a shoe fashion finally learned how to read.

sacai history: hybrid is not decoration, but structure

Sacai was founded in Tokyo in 1999 by Chitose Abe. Before launching the label, Abe worked as a pattern cutter at Comme des Garçons and later with Junya Watanabe’s team. Beginning with knitwear, sacai became one of the world’s clearest voices in hybrid design.

A sacai garment often contains two things at once: MA-1 and knitwear, shirt and jacket, pleats and sportswear, military and feminine, formal and casual. But the point is not simple docking. The question is where one garment begins and another ends. Abe’s real subject is the boundary line.

That is why sacai collaborations rarely stop at logo exchange. With Nike’s LDWaffle, two shoe histories were layered into one. With Dior, maison codes met sacai construction. With Carhartt WIP, workwear reality entered sacai’s language of layering. The Birkenstock collaboration belongs to this same lineage.

A reunion more than a decade in the making

The new collaboration resonates because the relationship did not begin from nothing. GQ reports that Abe worked with Birkenstock in 2014 on gladiator-inspired sandal boots for sacai’s Spring 2015 collection and platform Arizonas for Birkenstock’s former Japan-market sub-brand Tatami.

More than a decade has passed. In that time, sacai became a master of the power collaboration, while Birkenstock became a fashion object that can move from health store memory to runway credibility. The 2026 reunion is not just the same two names meeting again. It is a test of how both brands have evolved.

The map inside the names: Aoyama and Cassette

The names Aoyama 107 and Cassette 75 are not incidental. Aoyama points to Tokyo, to sacai’s flagship geography, and to the place where Japanese fashion is prepared for the world. The number gives the shoe a coordinate, a hint of address, a local memory.

Cassette points to Rue Cassette in Paris, where sacai’s Paris headquarters is located. That gives the collection two feet: one in Tokyo, one in Paris. German Birkenstock, Tokyo sacai, Paris runway — the triangle is written into the model names.

The Spring/Summer 2027 context: “The New Classics”

Sacai’s Spring/Summer 2027 men’s collection was framed around “The New Classics.” The collection returned to familiar menswear uniforms — preppy codes, tailoring, sweatshirts, utility, musical memory — and cut into them, layered them, shifted them. It did not reject classics. It made classics move.

In that context, Birkenstock made perfect sense. Few shoes carry “classic” and “everyday” as strongly. Because the silhouette is so familiar, small structural changes feel large. A strap multiplies. A clog becomes a sandal. A sandal becomes architecture. At sacai SS27, the footwear was not an accessory. It was a thesis statement.

Why this matters for Japanese fashion

Japanese fashion is powerful at material, structure, layering, dissonance, and the reinterpretation of daily life. Sacai is one of the clearest contemporary examples of that strength. BIRKENSTOCK x sacai shows how a Japanese designer can read a global classic and return it with another life.

This is not simply a Japanese brand collaborating with an overseas brand. It is a global standard passing through a Japanese structural imagination. Abe has not destroyed Birkenstock’s essence. She has protected it while changing how we see it.

That is why the collaboration matters. Japan’s fashion strength is not only surface. It enters the seam. It enters the overlap. It enters the space between function and memory. In this collaboration, that strength appears at the foot.

JAPAN.co.jp view

The Aoyama 107 and Cassette 75 are obvious candidates to become the sandals of 2027. More importantly, they show that collaboration can still mean something. Fashion has too many collaborations that are only names placed next to each other. Sacai and Birkenstock have produced something deeper: a collision at the level of structure.

Birkenstock’s footbed has always tried to stay close to the human foot. sacai’s hybrid design has always moved the boundaries of garments and objects. Together, they turn a walking tool into a design argument.

A summer sandal is an easy thing. But easy things travel deep into culture. That is the point of the Aoyama 107 and Cassette 75. Inside a light object are German footbed history, Tokyo construction, Paris runway context, and Chitose Abe’s idea of the new classic.

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