At the beginning of the Issey Miyake show, attendants armed with irons applied steam to the five colored fabric flags hanging from metallic poles along the runway. Slowly, the squares of fabric shriveled into the shape of a dress — including one with a silky pleated skirt and what appeared to be a knit bodice — that models slipped on in full view. It was a demonstration, both stunning and simple, of the new “Steam Stretch” process developed under the creative direction of Yoshiyuki Miyamae, who has taken over Miyake’s mantle of fabric innovation. For his second collection, the designer again looked to nature, this time the world of minerals. Crystal patterns abounded, as silky geometric appliqués on a biscuit-colored trouser suit, or a multicolored water-repellent lining on a nubby oversize orange coat.