There is no hard evidence, but everyone knows that when dusk falls on Mo'ili'ili, and the people at the Japanese Cultural Center of Hawai'i lock up and go home for the evening, local artist John Tanji Koga's strange plastic sculptures come to life, roaming around the gallery and generally making a racket.

During the day, for the benefit of visitors to the center, the sculptures remain still, as part of "Garden of Spirits," Koga's first solo exhibition. Made of plaster and resin, ranging up to eight feet in height, Koga's sculptures are perhaps more figurative than the artist intended; bulbous, featureless, asymmetrical, yes, but practically all of them have feet.

The show's opening reception drew more than 200 people — on a weeknight. Gallery director Christy Takamune attributes the remarkable turnout not just to general interest in Koga's work (Honolulu Magazine named him the "most collectible" local artist last year) but to general gratitude. "He helps with other exhibits," said Takamune. "When people call, he's there to help."

Viewed in isolation, Koga's individual pieces have the look and feel of classic American public art, the kind that has dotted parks and plazas in Mainland urban centers since the 1950s. Koga has dabbled in public art before.

His sculptural memorial in Kaka'ako Waterfront Park to local victims of drunk-driving accidents lends itself to straightforward interpretation, perhaps because of its poignant subject matter. Three human figures, each with holes where their hearts ought to be, representing grief and loss.

Holes are also a motif in "Garden of Spirits," but their function is harder to pin down. Two of Koga's "Spirit Tree" pieces (there are five of them) are composed of stacked, imperfect rings, increasing in diameter from top to bottom, atop stubby legs. The others are variations on that theme.

The "Spirit Tree" sculptures are blatantly "human," and this is where "Garden of Spirits" is a bit tricky. In the limited-edition book and information that accompanies the exhibit, Koga is adamant that the exhibition and its individual pieces not be over-interpreted, and that the "Garden" is meant to serve as a place for private contemplation.

But for Koga, the anti-interpretive emphasis is a case of form following function. Returning after a long break to working with plaster to make large-ish pieces, Koga took a while to get comfortable again.

"Going back to this raw material," he says, "the forms followed that. There's a whole engineering process that goes with that." And while the pieces begin life as individuals, the process of preparing a show ultimately unifies them. "It becomes an installation," says Koga. "As I walk through, it becomes an environment."

If the "Spirit Tree" pieces are human, or humanoid, then the "Spirit Stone" pieces interspersed among them is a barnyard menagerie of the strangest kind: lumpy, four-legged and often headless, but with an overall shape implying that there ought to be a head, somewhere. And the most anthropomorphic of all is "Sugar," with both arms and legs, an affectionate tribute to the late Tadashi "Sugar" Sato, creator of "Aquarius," the giant, aquatic mosaic on the floor of the state Capitol. Sato and other "old-time artists," says Koga, "helped lay the foundation." Sato died in June at 82.

Also in the exhibition are miniature resin versions of several of the larger pieces, created in editions of five. Made with collectors in mind, the miniatures also teach a specific lesson about the larger pieces, and about Koga's work overall: however spontaneous the curvatures and asymmetries in the "Garden of Spirits" appear, they are, in fact, the product of meticulous planning and execution. Koga is perhaps being a bit too humble when he suggests the pieces are merely there to provoke contemplation.

Visitors to the "Garden of Spirits" are likely to encounter Koga's sculptures with a mixture of familiarity and unfamiliarity. The sculptures invariably recall a cartoon, or an album cover, or a group show in a dingy basement gallery that you know you saw, but you can't quite place where.

A bit more specifically, they also recall the animal shapes that emerged from the "automatic writing" experiments of surrealist painters like Joan Miró and Jean Arp. The idea behind automatic writing, heavily influenced, like so many surrealist experiments, by Freud, was to bypass the conscious mind entirely in the creative process, going straight to the dark, dirty and confusing stuff located underneath.

That Koga's sculptures recall these experiments doesn't simply suggest that he is influenced by them. That would be too easy. The better answer is that the quasi-humans and quasi-animals lurking in "Garden of Spirits" seem familiar because they've emerged from the same murky and interesting place in which the bolder moments in 20th century art began.

And if you listen closely, late at night, you can hear them come to life.

Joel Tannenbaum is a freelance writer on art and literature.