It has more than double the coastline of Kauri Cliffs, although the US-owned site of the luxury lodge and golf course is much larger in overall size, he said.
Ownership of Tupou, a working farm, is spread across 16 titles, with a combined 2016 capital value of $16.9m.
Pleciak didn't want to say what the farm might sell for, other than it would be "in excess of" the capital value.
The 1439ha property is expected to sell for more than $17 million.
"It's very rare that there's something like this out there. The scale of it - the number of beaches and the coastline."
The property is owned by the families of the late Ray, Noel and Peter Josephson, the main shareholders in the Keans for Jeans New Zealand clothing business.
The business was famous for its 5m neon sign, outside Kean's Queen St store, of a cowboy in blue jeans and red bandanna twirling a lasso.
Tupou was covered in scrub when the Josephson brothers bought it in the early 1960s.
A farm manager and shepherd now live on the property and run the sheep and beef farm, which has an effective pasture area of 1150ha.
The property also includes a home, five baches and a beachside tennis court.
Family spokesman Rob Josephson said the family were selling "as the extended family is planning for the future".
