WeWork's escape plan is buried in the books at its Tokyo office

Masayoshi Son stood on stage in Tokyo earlier this month and told skeptical SoftBank Group Corp. investors that making WeWork Cos. profitable is not only possible, but will be "simple." Driving that confidence is WeWork's Japanese unit, which is already in the black and will be the springboard for a new service that could help the embattled office-sharing company.

While WeWork's board was still deciding in late October between SoftBank's $9.5 billion rescue package and an alternative from JPMorgan Chase & Co., Son spent two full days at the unit's head office in Tokyo, poring over the books, according to sources familiar with the matter.

Even before the deal was approved on Oct. 22, SoftBank was working with WeWork Japan on a subscription service called Passport that it plans to introduce worldwide, the sources said, asking not to be identified because the details aren't public.