Pitti marked a homecoming of sorts for Alessandro Dell'Acqua. The No. 21 designer showed his first collection here back in 1998, when he was designing under his own name. Now that No. 21 is humming along in womenswear, he's returned to Florence to debut its brother collection. "Pitti is very modern for men," Dell'Acqua said at the Biblioteca Nazionale, where he staged his presentation. "It's the big window."

The big window looked in on a small but giddy start. Numerologist that he is, Dell'Acqua showed 21 looks, which adapted straightforward sportswear and casual tailored clothing with what he called "an eccentric attraction." That amounted to sweatshirts, varsity jackets, tees, and cropped, tapered trousers made round and spongy in neoprene, glittery with beads and rhinestone details, or unexpected in bonded lace. (No. 21 womenswear has long borrowed the tropes of menswear, so here the fairer sex returned the favor.)

The road Dell'Acqua is treading is not untraveled, but no worse for the company. And like some of his contemporaries with a taste for young, poppy, Euro-prep separates—Guillaume Henry at Carven springs to mind—Dell'Acqua is reentering the market not at a designer price point but at a contemporary one. ("The price is contemporary," he hastened to clarify, "but the collection is not contemporary.") That's a space that may prove interesting to watch. As for where to watch it? In No. 21's case, Dell'Acqua is committed to keeping it on the men's fashion calendar, but in which city he couldn't yet say. Milan would be an obvious choice, but—notable at a time of Anglo-Florentine tensions, thanks to the competing schedules of London's menswear week and the Pitti Uomo fair—he was mulling the idea of the U.K., too. "London is very interesting for men," he said.