Since opening in Aoyama in 1994, Tokyo's Mizuma Art Gallery has moved around a bit -- first to Nakameguro and then, in 2009, to its present location. Occupying spacious quarters on the second floor of a new warehouse-style building across from the Sotobori moat, it sits conveniently between Ichigaya and Iidabashi stations right in the middle of town.

The current exhibition (on display till February 7) does not really fit that mold, however. Photographer Masao Yamamoto's Shizuka=Cleanse series offers high-contrast monochrome closeups of small clumps of nature -- specifically, roots and rocks. Carrying no weighty messages, they simply exist on their own terms. One would not be surprised to find these prints untitled, but Yamamoto has given them names, in English no less, that rarely appear to have anything to do with the object presented: Dust, Ephemeral, Reborn, Mamma, Hop, Unite. How to relate these images to their appellations is clearly up to the viewer. Granted, a few are evocative -- Torch, Hunter, Monkey Stone -- and Pegasus, a jagged snag of tree root that really does look like a flying horse.

Until recently, Yamamoto has shown a preference for the unpremeditated snapshot: cityscapes, landscapes, and instants of human or animal behavior generally captured out of doors. His affinity for nature has grown deeper, apparently, since he moved out of Tokyo to the foot of Mt. Yatsugatake, a volcanic massif in central Japan surrounded by an expanse of grassland and forest. On his long daily walks, he says, he comes upon strange rocks and root formations that he digs up and carries back to his studio. There he arranges them against a black background and illuminates them from various angles. The complex lighting is a sort of "sculpting" process that shapes the object and brings it to life. As one visitor noted, these silent fragments of nature have spent long years buried in the earth, brimming with pent-up energy but unable to release it. Now liberated from their confines, the roots and stones radiate a nearly visible life force, akin to a flower blooming. This notion is reinforced by at least one of his titles, "Free at last," given to a powerful shot of a root mass that virtually explodes with sharp spikey protrusions.

These photos hang on the walls of Mizuma's main gallery, a high-ceilinged white cube. In the center, a table displays an array of earlier prints by Yamamoto. The stylistically helter-skelter montage provides puckish contrast to the meticulous, controlled methodology of the works on the wall.

Then comes the kicker. Atop the tree root, Yamamoto has also balanced a tiny figurine -- a little man, wearing something akin to a top hat and tails -- which he picked up at a souvenir shop in a resort town near his home. What are we to make of this? Is it the artist himself, posing on one of his favorite natural formations? Or just a dig at his viewers, admonishing us not to make too much of this Zen stuff? All one can tell for sure is that, his communing with nature notwithstanding, the photographer has retained his street-smarts -- a sense of the ironic that refuses to take the metaphysical tinge of his recent work too seriously.