Before his abrupt departure from SoftBank Group last year, Katsunori Sago was seen as a potential successor to billionaire founder Masayoshi Son. He’s now charting his own course in startup investments.

SoftBank’s ex-Chief Strategy Officer joins a growing cadre of Son’s former lieutenants who have caught the venture capital bug. Former Chief Operating Officer Marcelo Claure, who left earlier this year, is deploying billions through his family office. Rajeev Misra, who helped Son set up the initial Vision Fund, has stepped down from his role as a corporate officer and is launching his own fund.

Sago, 54, is putting his own money into Japanese startups such as Ispace, which is developing a moon lander for NASA‘s Commercial Lunar Payload Services project, and renewable electricity generation forecaster Sustech. He also backs mortgage lender Aruhi and online real-estate brokerage platform Tsukuruba, hunting for investment returns that will help fuel his long-term bets.