Until recently, the most famous retail billionaire to hail from Japan was Tadashi Yanai, the low-profile founder and architect of the casual-wear empire Uniqlo. This week, however, a new contender has emerged for that crown: Yusaku Maezawa, a fashion billionaire who recently posted an online advertisement for a wing woman to accompany him on the first SpaceX flight around the moon — and through life.

Who is he?

Mr. Maezawa, 44, is the renegade founder of Zozotown, Japan’s largest fashion retailer. He made headlines around the world in 2018 when it was revealed that he would be the first private passenger to fly around the moon by SpaceX, the company owned by Elon Musk. With a penchant for flashy purchases, Mr. Maezawa, a college dropout, has long been considered a master self-promoter. This makes him something of an anomaly in Japan, which has one of the world’s most conservative corporate cultures.

How did he make his money?

Mr. Maezawa has a net worth of $3.6 billion, according to the Bloomberg Billionaires Index. His fortune is largely thanks to Zozotown, an online fashion marketplace for cool Japanese and Western brands that he started in 2004. Today, the site features about 7,300 brands with more than 730,000 items and is the largest fashion mall in Japan; its parent company, Zozo Inc., is listed on the Tokyo Stock Exchange.

In September, Mr. Maezawa resigned from the management team of Zozo after selling a 30 percent stake in the company to Yahoo Japan, which is owned by SoftBank, for $2.3 billion. In November, he posted a video on YouTube that filmed him visiting a Tokyo bank branch to update his bank book after the deal, which showed a new balance of around 100 billion yen ($900 million).