Watanabe got married to his first wife in 1983 and had two children Dai and An who are both actors now. They got divorced in March 2005 before Watanabe married Minami in December of the same year.
When asked about the alleged affair, Watanabe's agency said that he is overseas at the moment and that they will check with him on this once he returns. As for Minami's agency, they said that she is on long leave until May so they have no idea where she is now.
In response to the affair rumours, Watanabe's photo has been taken off the CM on the homepage of Daiwa Securities. He had been featured in their CM since 2015 and his TV CMs were scheduled to run until 31 March. As the company is trying to ascertain the facts behind this allegation, they decided to remove his image from their website and will review his CM deal in the meantime.
Sources: Real Live / Sports Hochi