I'm often asked the question: "What characterizes Japanese contemporary art?" At the risk of over-generalizing, I usually reply that two qualities recur among artists at the vanguard of this country's creative culture -- an obsessiveness vis a vis the subject, or an obsessive attention to detail in the actual execution.

Consider the highly finished work of Takashi Murakami and Mariko Mori. These two artists' inspiration -- in Murakami's case manga, anime and otaku culture; for Mori, Eastern mysticism and New Age spiritualism -- find form in pieces which are high-tech, very polished and large scale.

In the other camp we find artists such as Yayoi Kusama, who for 40 years has been painting polka-dot and net patterns; and Makoto Sasaki, whose "Heartbeat Drawings" are wall-covering red-pen-on-paper works which illustrate, hospital ECG-style, the "blip, blip, blip" of his heartbeat.

There is something seductive about this second sort of artistic activity -- its hypnotic commitment to a single subject leaves the viewer with little choice but to search for deeper messages. It is also highly conceptual -- On Kawara, whose "date paintings" depict, in plain text, nothing but the date that they were painted, is regarded as one of the fathers of Conceptual Art.

Of course, those who criticize such art argue that these artists have nothing to say, and only use repetition to trick us into looking for meaning that isn't there.

What makes Satoshi Matsuyama's fixation different from his contemporaries' is that it is not with something stark and steady like dots or heartbeats or passing time, but with women's breasts.

Matsuyama, 34, is now showing at Gallery Art Point on Tokyo's Ginza art strip. "Spring and Summer" comprises 11 new paintings, done mostly large scale and in oil on canvas, although there are several smaller acrylic and colored pencil-on-paper works here as well. The models are, no surprise, young and wide-eyed and exposing their breasts.

Matsuyama's 1998 solo show, "I Love Boobs," at the Art Space Niji in Kyoto, marked a turning point in the artistic development of this Kyoto City Museum of Art graduate. Until then, Matsuyama's studied creations were -- depending on how you took them -- either totally derivative or intentional homages to artists such as Kusama and American Paul McCarthy, whose styles he freely appropriated. With "I Love Boobs," the artist discovered that if he focused on what he liked, making art would be a lot more fun.

And so, there followed from Matsuyama a series of ceramic sculptures of breasts; a series of hundreds of paintings of breasts, often pictured being violently groped by male hands; and even a rubbery "personal oppai" device, which allowed the bespectacled and nerdy-looking artist to prance and pose while wearing his very own set of big breasts.

Sexist and immature? Yes, but this didn't seem to register with the judges of the Kirin Contemporary Art Award, who bestowed the prize on Matsuyama in 1998, and again in 1999. In 2000, he was invited to show at the Kyoto Woman's University and last year he exhibited at the head office of leading brassiere manufacturer Wacoal.

The paintings in "Spring and Summer" are not without merit, technique-wise. All titled "Fashion Illustration," they depict their subjects partially clothed in a selection of topless outfits designed by the artist and sure to appeal to breast-obsessed men (and women) everywhere. On close inspection one finds a naturalistic treatment, with faint blemishes and blue veins visible in the skin tones.

While Matsuyama is certainly no great master of the nude, he is a more than capable painter who does know his breasts. And the artist is racking up sales with "Spring and Summer," his fifth solo show this year -- most of the larger, not inexpensive works were already accounted for midway through the run of the exhibition.

Again, when presented with work that zealously focuses on one particular subject, one wants to delve deeper. But try as I might, the only message I detected in Matsuyama's new paintings -- and in the wide selection of earlier work the gallery displays here in catalogs, and in his recent success in general -- is that the artist has found, among collectors and other players on the local contemporary art scene, a large number of people who are just as snickeringly puerile as he is.