The 25-year-old rugby player was found dead in Bay of Plenty last Monday.
Coroner Louella Dunn has made interim suppression orders around the circumstances of his death.
Wainui joined the Chiefs in 2018 and played 44 games for the Hamilton-based Super Rugby franchise, having previously played for the Crusaders.
He was first picked for the Māori All Blacks in 2015 and made 10 appearances for them.
Earlier this year, Wainui became the first player in Super Rugby history to score five tries in one game.
