Japanese dealmaking was resurgent in the second half of 2020, with acquisitions dropping only slightly from 2019 to about $140 billion (¥14.6 trillion) after the pandemic depressed deals in the first half of the year.

The momentum is likely to continue into 2021, M&A advisers say, with a pipeline of already agreed deals still to be announced. Pent-up demand, towering cash piles and external forces that could make 2021 among the most active years yet.

"Japanese companies are heading into 2021 with more cash and more firepower, having sold some non-core assets and consolidated their operations, and will turn again to outbound acquisitions” said Ken LeBrun, a partner at law firm Davis Polk Wardwell in Tokyo. "When that’s going to be — first, second, or third quarter — is not perfectly clear.”