Tours-and-activities software provider Xola had secured a $6 million capital-raise in February, according to a financial filing — which did not reveal the main backer.

Today Rakuten, Japan’s cross between Amazon and eBay, has revealed that its venture arm led a $5 million Series A equity investment in the San Francisco-based startup.

When asked about the discrepancy with today’s announcement of $5 million with the $6 million mentioned in the SEC filing, a spokesperson for Xola said, “The number that we go with, in laymen’s terms, is $5 million” — which follows on an earlier $1.8 million capital raising.

With a $2.5 million contribution, giant Rakuten Inc has become an investor in Xola, which has 30 employees. In a statement, it said:

“Rakuten, by investing in Xola, a company with innovative technological ability in the tours and activities industry, is taking the lead in invigorating the travel-related tour and activity market that is expected to grow in Japan even further.”

Xola also said it has “averaged 500% year-over-year growth over the last two years.” Besides Rakuten, its investors to date have included Stanford University StartX Fund, Michael Burry, and Scott and Brett Crosby, co-creators of Google Analytics.

Xola it said that it “offers a cloud-based reservation management platform that tour providers need to efficiently run their businesses. It also lets companies connect their tour availability in real-time with resellers via Xola’s state-of-the-art API.”