Ten years ago, there was barely any work by Kazuo Shiraga to be had on the market. In 2003, the one work that came up for auction was a 1961 painting entitled Chizosei Shomenko, which sold at French auction house Cornette de Saint-Cyr for €40,340, roughly $46,000. In 2008, shortly after the artist’s death, a 1962 painting called Tenkosei Kaosho set a record for the artist at auction when it sold for €726,650 (approximately $1.2 million).

In 2013 that record would be set anew when a collection of Gutai works by the Parisian gallerist Rodolphe Stadler (who had given Shiraga his first solo show outside of Japan in 1962) went to the auction block in June at Christie’s Paris. At that sale, Chiretsusei Katsusemba, a 1961 painting brought in €1,665,500 (about $2,178,263) over twice the high estimate, indicating that there was something of a run on Shiraga’s work. This past summer, sales entered a new ballpark when Gekidou Suru Aka, a painting from 1969, sold at Sotheby’s Paris for €3,905,500, roughly $5,320,119. Since 2009, when the artist’s average price at auction was $79,479, Shiraga’s market has seen a 400 percent jump; roughly 30–40 works have come up at auction per year. His average price today is $481,534.

“Do what no one has done before,” was the mandate that Gutai founder Jiro Yoshihara gave his fellow members. Gutai, which could mean “embodiment” or “concreteness” depending on how you translated it, was founded in Osaka in 1954. While the group was incredibly diverse, and there was no aesthetic link, its members came together over their approach to art and their desire to do something that had never been done before, like painting with the body, or selling paintings from a vending machine that hid the artist inside.

In Shiraga’s own form of action painting, he eschewed brushes in favor of dripping paint directly onto the canvas, or painting with his bare feet or entire body, moving it across a canvas while hanging from a rope. By this method, Shiraga has said he aimed to show “traces of action carried out with speed.” His techniques resembled those of the Abstract Expressionists who similarly emphasized spontaneity and directness of expression and his work is said to have influenced such artists as Yves Klein, Allan Kaprow, and Jackson Pollock.

French critic Michel Tapié was initially responsible for bringing the Gutai artists to the French market in the 1960s. But after Yoshihara’s death in 1972, the group was largely forgotten. While there used to be only a handful of collectors for work by Gutai members, the recent flurry of shows has increased that number, and very dramatically. But all of this is indeed recent, beginning more or less in 2013 after several significant museum shows explored postwar Japanese art, including MoMA’s “Tokyo 1955–1970: A New Avant-Garde,” the Guggenheim’s “Gutai: Splendid Playground,” and LA MOCA’s “Destroy the Picture: Painting the Void, 1949–1962.” In February the Dallas Museum of Art will open “Between Action and the Unknown: The Art of Kazuo Shiraga and Sadamasa Motonaga,” exploring the careers of both Gutai members.

Gallery shows have also been giving more exposure to postwar Japanese artists. Hauser & Wirth‘s 2012 show “A Visual Essay on Gutai” displayed masterworks by 12 Gutai members, including Shiraga. Blum & Poe’s “Requiem for the Sun: The Art of Mono-ha” looked at a Japanese group active in the late 1960s and ’70s exploring the relationship between natural and industrial objects.

“There is a general lift in attention and prices for Gutai,” Boris Vervoordt told artnet News over email. Vervoordt heads up the art, antiques, and interior design program at Belgian art and design enterprise Axel Vervoordt, a key dealer in the art of Gutai members. Axel Vervoordt began collecting Gutai art in roughly 2005, when he took a trip to Japan with Mattijs Visser, curator and founding director of the ZERO foundation. They were doing research on the links between Gutai and Germany’s ZERO movement, and Visser would include some Gutai artists in his 2006 international ZERO show at the Quadriennale Düsseldorf.

Even with the rising interest in Gutai, Shiraga is still a standout performer in the group. He is the highest performing member of Gutai at auction, by a significant margin.

The next highest member at auction is Yoshihara, whose record was set in 2012 in Hong Kong by a 1966 painting, Untitled, of a white wavy rectangular outline against a black background, which sold for HKD 5,360,000 (roughly $690,090). Cofounder Shozo Shimamoto’s record was set in a 2009 Christie’s Paris sale of an oil on glass and canvas work that sold for €49,000 ($68,560). Takesada Matsutani’s record was set in a 2013 Japanese sale of a white acrylic and glue painting for JPY 15,522,500 ($156,091).

The recovering Japanese market and the falling yen are also partly responsible for the spreading interest internationally of the work of Gutai artists. According to one recent report in Reuters, a weaker yen is known to stimulate business and investor confidence because it gives exports (a significant force in Japan’s economy) a boost. Collectors are thus prone to sell artwork to foreign collectors.

“Worldwide, some important collectors and institutions are looking for the work,” said Vervoordt, who claims that Shiraga’s market is split roughly 50-50 between museums and private collections.

On that trip, on which Axel Vervoordt met Shiraga, along with other living Gutai members, the art dealer became convinced of the quality and historical importance of the group and has shown them at shows and fairs ever since—including at the 2007 show “Artempo” at Palazzo Fortuny in Venice.

Vervoordt brought a set of Shiraga canvases to Maastricht in March, where gallery director Robert Lauwers told the New York Times that Gutai artists were selling more successfully than ever. “They are getting harder to find,” he said at the time. At its Hong Kong gallery space, the gallery has a show of Shiraga’s work on through November, the first solo show of the artist in Hong Kong.