A Japanese retail billionaire, rather than a Silicon Valley wunderkind, is the biggest beneficiary of Lyft Inc.'s impending initial public offering.

Hiroshi 'Mickey' Mikitani's e-commerce group Rakuten Inc. owns 13.1 percent of the ride-hailing company, offering documents show. That would be worth more than $2.9 billion if Lyft goes public with a valuation in the middle of its anticipated range of $20 billion to $25 billion.

Rakuten, Japan's largest online retailer, owns an eclectic assortment of side businesses including a professional baseball team and a bus service. It first invested in Lyft in 2015, acquiring an 11.9 percent stake for $300 million.

'We have seen the future and this is it,' Mikitani, now 53, said at the time.

Silicon Valley venture capital firm Andreessen Horowitz, a Lyft investor since 2013, is the second-largest owner with a 6.3 percent holding that would be worth about $1.4 billion.

The stake held by Lyft's actual wunderkinds, co-founders John Zimmer, 34, a former Lehman Brothers analyst, and Logan Green, 35, is relatively small after multiple dilutive funding rounds. Green, Lyft's chief executive officer, and Zimmer, its president, each hold shares worth about $113 million at the middle valuation. By contrast, Travis Kalanick, who helped launch rival Uber Technologies Inc., owns 7 percent of that business even after selling almost a third of his stake last year. He and fellow co-founder Garrett Camp are both billionaires, given Uber's $72 billion private-market valuation.

It has already been a lucrative year for Rakuten founder Mikitani, Japan's sixth-richest person with a $4.9 billion fortune, according to the Bloomberg Billionaires Index. His net worth has climbed by $680 million in 2019, fueled by a 20 percent surge in Rakuten shares.

Rakuten also owns a stake in Middle East ride-hailing firm Careem, which is in advanced talks to be acquired by Uber in a potential $3 billion deal, people familiar with the matter said earlier this week.