“Is that the show for the giant dresses?” was the question heard around the fashion world this week. Tomo Koizumi is the designer, and, yes, the dresses are huge. But to write off Koizumi as a confectioner is shortsighted. Up at Marc Jacobs’s Madison Avenue store, where Koizumi held a first fashion show, put on with the help of Katie Grand, Guido Palau, Pat McGrath, Jin Soon, Tabitha Simmons, Anita Bitton, and a cast of A-list models, the Japanese designer proved his mettle.Grand had orchestrated the whole affair, having discovered Koizumi on Instagram through her friend Giles Deacon....…“Is that the show for the giant dresses?” was the question heard around the fashion world this week. Tomo Koizumi is the designer, and, yes, the dresses are huge. But to write off Koizumi as a confectioner is shortsighted. Up at Marc Jacobs’s Madison Avenue store, where Koizumi held a first fashion show, put on with the help of Katie Grand, Guido Palau, Pat McGrath, Jin Soon, Tabitha Simmons, Anita Bitton, and a cast of A-list models, the Japanese designer proved his mettle.Grand had orchestrated the whole affair, having discovered Koizumi on Instagram through her friend Giles Deacon....WW…