Mapusua is one of four new appointments made by the union as it seeks to align itself with its new strategy developed by the board over the past year.
Mapusua, who also played for Samoa, has just returned from Japan where he was a player coach with the Kamaishi club.
He will join Jason Macdonald, who is also a coach development officer.
Macdonald, a former Otago and Highlanders hooker, has been with the union since 2011.
The new strategy has the union putting more of a focus on coach development and retention and player retention.
The union has also appointed Simon Wallace as club and schools liaison officer.
He will work in with clubs and schools to help them in their administration of the sport.
He has worked for the union since 2014 as rugby operations administrator.
The union has appointed Matt McLennan as its new commercial manager.
He is originally from Dunedin and the union said he had extensive experience in the development and implementation of commercial strategies in the sporting sector.
He previously worked at Westpac Stadium in Wellington handling commercial operations.
The union has lost more than $200,000 in commercial sponsorship in the past financial year and needs to boost its income.