Mason was raised in New Zealand having moved to Tauranga aged 2 and lived New Zealand until 2017 when Mungo moved to the United States to further his studies at Chicago-Kent College of Law upon the completion to his LLB degree at the University of Waikato which led to him being signed to play in the fledgling Major League Rugby competition in 2018 before moving to Scotland where Mungo was selected to play for Scotland in the 2018-19 World Rugby Sevens Series.