KURASHIKI, Japan

Carter Devries, a 51-year-old who works in sales and marketing in Louisville, Ky., is a self-described jeans aficionado who researches brands on Instagram. But it’s not an American label he covets. It’s a high-end, niche Japanese one touting labor-intensive craftsmanship and individual details—and a price tag of up to $2,000. “I would really like to own a pair of Momotaros,” he says, dropping the name of the cult Japanese line.

The...