Elderly Japanese, among the world's richest retirees, are flocking to inheritance advisers, tackling historical taboos on discussing death and providing a rare avenue of growth for the country's brokerages and banks.

Trillions of dollars parked in savings accounts are set to be released in the coming years as Japan's death rate climbs and new, more onerous inheritance tax rules kick in.

The shift is attracting investment from companies such as Nomura Holdings, Daiwa Securities Group and Mizuho Financial Group, which are ramping up offerings of inheritance-related services and products, hoping to lock in a new generation of customers.