Upon entering his current exhibition at the Hiroshima City Museum of Contemporary Art (MOCA), it is clear that although what he does can be described as making art, Tsuyoshi Ozawa is not an artist.

Born in Tokyo in 1965, Ozawa first gained notoriety in the 1990s through his "Nasubi Gallery" series of guerrilla exhibitions installed in wooden milk boxes in the streets of Tokyo's posh Ginza district. Inverting the Japanese pronunciation of the historic Nabis Gallery, located in Ginza, the "Nasubi Gallery" responded to the then-predominant rental-gallery system through which venues charged artists for exhibitions. With their interiors painted white to resemble a gallery space, the rectangular milk boxes provided Ozawa and other emerging artists an opportunity to exhibit their works without the customary prohibitive costs.

Since then, he has developed a reputation as a shape-shifting prankster whose works express irreverence toward high art through their use of collaboration and alter egos. Titled "The Invisible Runner Strides on" and organized by chief curator Yukie Kamiya, the MOCA exhibition provides a loose introductory framework to Ozawa's career by focusing on the artist's long-term serial projects.

Greeting visitors to the exhibition is a collection of "Nasubi Gallery" works installed on plinths and hung on the walls of a main gallery. On display are works from the project's inception in 1993, such as Ujino Muneteru's mini wet bar with an arrangement of travel-size liquor bottles resting on a glowing blue light, as well as more recent examples such as a box by Vietnamese artist Dinh Q. Le^, which is painted with a depiction of lotus fields that serves as the backdrop for lotus-themed tchotchkes.

Other notable contributors include Yayoi Kusama, who has filled a box with white, tentacle-like sculptures, and Chinese artist Lin Yilin, who has pasted his phone number and e-mail address over a picture of himself in mid-performance in a winking solicitation to international curators. Works by Ozawa himself include a box that houses a black-and-white geometric abstraction on a miniature canvas.

However, incorporated into an exhibition format they once critiqued, the "Nasubi Gallery" works lose the sense of urgency they may have conveyed on the streets. Instead, they come across as a collection of taxidermic specimens, bearing the anatomy of artworks but lacking the vitality that encourages interaction from the viewer.

Begun in 1988, the "Jizoing" photographs circling the walls of an adjacent gallery also conjure expedition trophies, but maintain their feral edge. These photographs result from Ozawa's trips to places ranging from the Tokyo neighborhoods of Ueno and Otsuka to Wuhan, Tehran, Moscow and Uganda's Kibale National Park. Each monochrome photograph, tinted blue to suggest the sky at twilight, depicts either an actual Jizo votive figurine or its outline, recognizable by a characteristic elliptical torso and head silhouette, hidden in a public setting. (The bodhisattva Jizo is a protector of travelers, women and children whose figure often lines roadsides in rural Japan.)

At times, the photographs coincide with historic moments, as in ones taken at Tiananmen Square in 1989 or in Kobe in 1995. At others, they mock contemporary journalism by replacing humanistic themes with an oblique icon. In the case of "Jizoing: Peshwar [Pakistan]" (1988) the metal smith squatting behind his stall in an open-air market takes part in an incidental documentation. His stare directed at the camera lens — familiar from international wire service profiles of developing world penury — is not really intended for Ozawa's camera, which ultimately seeks out the Jizo outline tacked to a post behind the man's shoulder.

This kind of misdirectional poetry appears later in "The Seven Wonders of Hijiyama, Hiroshima," a large-scale model made out of paper recycled from origami cranes that reproduces the topographical contours of Hijiyama, the mountain in downtown Hiroshima on whose peak the museum is located.

Commissioned for the exhibition, Ozawa's interactive installation performs an excavation of Hijiyama, which shielded the Danbara area of the city from the Aug. 6, 1945 atomic blast. Corresponding to the locations of their real-world counterparts, containers embedded within the model open to reveal short texts about various landmarks on the mountain, with commemorative stamps for visitors to collect as they complete the circuit of attractions.

The seven sites that Ozawa has chosen include the plinth on which a statue of Tomosaburo Kato (who served as prime minister from 1922-23) once stood before it was melted down for metal during World War II; a wooden house that survived the atomic bombing but is scheduled to be torn down this year; and NHK broadcasting towers that face obsolescence when analog TV transmissions conclude in 2011.

Assuming the breezy tone of educational writing typically found at zoos or science parks, the texts imbue the installation with a light-hearted irony, while implying that contingency inevitably trumps memory — even in a city whose identity is tied to remembrance.

Like the "Nasubi Gallery," the other works in this exhibition largely function better as conceptual exercises than actual displays. For example, Ozawa's "Vegetable Weapon" series of photographs, begun in 2001, features young women holding model rifles fashioned out of groceries, which are then disassembled for cross-cultural exchange meals. Yet once their purpose is revealed, the images, installed in a phalanx of double-sided frames hung from the ceiling, lose their ability to arouse curiosity. Evoking a stylish Uniqlo bohemianism, they could be part of an elaborate marketing campaign.

Similarly, "Carpet from the Sky" (2006) recycles PET bottles found at sites around East Asia into synthetic fiber carpets, samples of which are hung from the ceiling of a different gallery.

Taken as a whole, "Invisible Runner" offers a much-appreciated opportunity to assess Ozawa's work after the artist's previous large-scale solo exhibition, "Answer with Yes and No!" at the Mori Art Museum in Tokyo in 2004. Perversely, Ozawa's willingness to open his creative process to other participants results in an odd mix of didacticism and chance, obtuseness and lyricism. The image that emerges in Hiroshima is that of a quixotic scientist conducting a series of elaborate field studies, not knowing where the results will take him.

"Tsuyoshi Ozawa: The Invisible Runner Strides on" runs till Sept. 27 at the Hiroshima City Museum of Contemporary Art; admission ¥1,030; open 10 a.m.-5 p.m. (closed Mon.). For more information visit www.hcmca.cf.city.hiroshima.jp