A few staple pieces pervade Needles' seasonal collections, but none are as important as its signature track pants, a timeless classic of contemporary Japanese streetwear. Keizo Shimizu, the man who oversees Needles and parent company Nepenthes, explores the garments' origins for the first time in a lengthy interview with the Japanese Nepenthes website, thankfully translated into English.

Shimizu founded Needles in 1995, seven years after he launched Nepenthes. It took a decade and change for Shimizu to realize Needles' first track pants in 2008, having absorbed influences from vintage sportswear, American films, and like-minded labels like COMME des GARÇONS. The debut model was surprisingly similar to Needles' contemporary versions: a washable, shape-retaining polyester or velour body finished with five stripes and the butterfly branding, named for and inspired by Papillon.

Design cues came primarily from the [adidas] ATP tracksuits that Shimizu wore as a Phys Ed. student. "I liked the daring approach of increasing the number of stripes from three to five," Shimizu said. "We develop exclusive fabrics for every collection, and I try not to use the same color scheme. ... Though I’ve used our signature color combination of black and purple a few times, the actual color of each black fabric is slightly different, while the purple shades of the fabric tapes also vary from violet to reddish ones."

The Needles track pants were love at first sight for Shimizu, but not so much for buyers. The track suit launch was "was actually terrible," Shimizu laughed. Regardless, he continued wearing them, and Japanese customers followed suit. Eventually, Needles' track pants received international acclaim thanks to tastemakers like A$AP Rocky, whose AWGE co-created its own collaborative Needles track gear several times. Shimizu never sought out these kinds of collaborations himself, though — all the would-be partners come to him first, and he's usually all too happy to oblige.

Even as demand swells for Needles' mohair cardigans and pieced-together shirts, the track pant remains at the foreground of Needles' output. It still inspires various collaborations — even beyond jackets and trousers — and remains key to the brand's output. Even today, it's Shimizu's favorite part of each Needles collection. "I always [design] it first," he said. "It's the core."