Contagious energy is what Humberto Leon and Carol Lim are all about. Since their arrival at Kenzo in July 2011, they have turned the somewhat dormant brand into an achingly cool line, delivering great clothes and accessories for boys and girls. When the two California natives chose downtown New York to launch Opening Ceremony in 2002, they managed to capture the essence of fashion within a retail environment, mixing street style cred with fresh proposals. By Philippe Pourhashemi