Merrifield left TBWA in November 2011 after nine years with the creative network. He first joined TBWA Japan in 2003 as chief creative officer and took on his regional role in 2006.
During his time with TBWA, one of his most acclaimed campaigns was the Impossible Sprint for adidas.
He joined Google at the start of the month.
Update: This article was amended to reflect that John Merrifield will not be based solely in Tokyo.