City girl goes to the mountains and winds up with more than just her head in the clouds. That was the theme Commuun's Kaito Hori and Iku Furudate established for Spring. The show began with sporty separates like tanks, windbreakers, and track pants accessorized with oversize backpacks and canvas belts with plastic snap-in buckles. There was also the occasional runway-only harness binding a model's rear end. As the girls made their way up the imaginary hill, the clothes took on volume; an electric blue parachute silk peplum decorated a crinkly silver minidress, and a simple sleeveless shift in a red grid jacquard was finished at the hem with a drawstring, like a parka. The cocktail dresses that closed the show came (you guessed it) with cloudlike billows spilling down one side or floating out nearly an arm's length beyond the bodice. If most of them looked too avant-garde for their own good, the final two, one in black and the other white, had crossover potential. What's most impressive about Commuun is how everything is made with organic materials. As the designers put it themselves, "The true challenge was using natural fabric for high-tech looks, instead of synthetic." And it's not just an exercise; Saks recently started selling the Japanese label.