The Japanese Ivy Style , also known as Ametora (a portmanteau of "American Traditional") or Japanese Preppy , is a Japanese fashion movement centered on the adoption and perfection of classic American Preppy style. It first gained prominence in the 1960s, pioneered by tastemaker Kensuke Ishizu through his brand VAN Jacket and publications like Men's Club magazine. The aesthetic was famously codified by the 1965 photobook Take Ivy , which documented the authentic campus style of American Ivy League students and became a definitive guide for a generation of Japanese youth.

Unlike its American counterpart, which grew organically from an upper-class subculture, Japanese Ivy is a highly studied and reverent interpretation of the fashion. It is characterized by an obsessive attention to detail, authenticity, and craftsmanship, often resulting in looks that are more "perfectly" preppy than those found in its country of origin.

The history of Japanese Ivy Style began in the conservative, post-war Japan of the 1950s and 60s, a time when men's fashion was dominated by sober, formal suits. The movement was protagonized by Kensuke Ishizu, who founded the brand VAN Jacket in 1951 to introduce the American collegiate look to Japan. Initially, the style was seen as rebellious; in 1964, a group of youths known as the Miyuki-zoku were famously rounded up by police in Ginza for wearing Ivy-style clothing. However, a major turning point came that same year when Ishizu was commissioned to design the uniforms for the Tokyo Olympics, an event that legitimized the aesthetic and shifted public perception from seeing it as a sign of delinquency to a mark of modern good taste. Though the original Ivy boom faded by the late 1970s with the bankruptcy of VAN Jacket, the style was preserved and perfected by Japanese enthusiasts, leading to a global resurgence in the 2000s when the rest of the world rediscovered Japan's dedication to the look.

Japanese Ivy Style, or Ametora, is defined by an almost academic devotion to the rules and details of classic American Preppy clothing. While the core garments are the same (button-down oxford cloth shirts, chinos, natural-shoulder blazers, loafers, and cardigans), the Japanese approach differs in its meticulous execution. Whereas American Preppy can have a casual, lived-in quality, the Japanese interpretation focuses on achieving a perfected, authentic ideal. Every detail is considered, from the precise roll of a shirt collar and the width of a tie to the correct way to crease a pair of trousers. This reverence for craftsmanship and authenticity means that Japanese-made Ivy clothing is often considered to be more "correct" to the original mid-century ideal than its modern American counterparts.

The dissemination and codification of Japanese Ivy Style were driven by influential media. The single most important document is the 1965 photobook Take Ivy , a collaboration between VAN Jacket and Men's Club magazine. Photographed by Teruyoshi Hayashida, it captured real Ivy League students on American campuses and became the definitive "bible" for the style in Japan.

Magazines were also important, with Men's Club serving as the primary guide throughout the 1960s and 70s, teaching readers the specific rules and nuances of the aesthetic. In later decades, magazines like Popeye helped revive and reinterpret the style for new generations. More recently, the history of the movement was detailed for a global audience in the 2015 book Ametora: How Japan Saved American Style by W. David Marx.