SoftBank's first female director to leave after challenging Masayoshi Son

Yuko Kawamoto, a professor at Waseda University, will step down on June 23 after just one year in the role, SoftBank said in a statement on Friday

SoftBank Group Director Yuko Kawamoto plans to resign from the company’s board in June, removing an outspoken board member who has clashed with controversial founder Masayoshi Son over governance issues.

Kawamoto, a professor at Waseda University, will step down on June 23 after just one year in the role, SoftBank said in a statement on Friday. She was the first woman to ever serve on the board and its only female member, although another one has been nominated.

In an unusual move, Kawamoto penned a long message about her time at SoftBank, posted on the company’s website. While she praised Son for his decision making, speed and willingness to change his mind, she also said the company needs more internal checks, better governance and more people who can stand up to Son.

“SBG needs to formulate a form of governance that allows Masa to fully demonstrate his talents, which can then be integrated into shareholders’ value,” she wrote. “This does not imply restrictions or constraints but rather an oversight function that allows the organization to reach its full potential.”

SoftBank’s biggest challenge is coming up with a succession plan for its founder, Kawamoto said. She said she is stepping down after one year because of her appointment as a commissioner of the National Personnel Authority.

Also departing from the board in June are Son’s long-term lieutenant Ronald Fisher and Arm’s Simon Segars. Z Holdings’s co-Chief Executive Officer Kentaro Kawabe, Koei Tecmo Holdings’s Chairman Keiko Erikawa and Kenneth Siegel of Morrison & Foerster will take their seats after shareholders approve the appointments at a general meeting.

SoftBank’s board has lost several of its most independent voices in recent years, the kind of directors who could push back on Son’s decisions. Shigenobu Nagamori, the outspoken founder of motor maker Nidec Corp., stepped down in 2017. Fast Retailing Co. CEO Tadashi Yanai, who had been on the board since 2001 and was a rare voice of dissent, left at the end of 2019. Alibaba Group Holding co-founder Jack Ma left last June, after 13 years on the job.

SoftBank has been buffeted by a series of missteps over the past year, including a botched investment in WeWork and a risky foray into derivatives trading. Kawamoto flagged that SoftBank often races so quickly to execute Son’s ideas that the infrastructure isn’t always in place to handle them. “Sometimes, therefore, rules come after the decisions are made, and some might say the company has some weakness in that regard,” she wrote.

One area where Kawamoto had a particularly sharp disagreement with Son was over his personal stake in a subsidiary overseeing SoftBank’s controversial options trading program.