The Tokyo Fire Department will launch a helicopter-based unit called Air Hyper Rescue to battle fires in high-rise buildings, the Japan Times reported on June 29,2015.
From Aviation Today:
[T]he Air Hyper Rescue unit would be established by April 2016, and would use a helicopter with a 660-gallon water tank and water cannons capable of discharging approximately 160 gallons per minute horizontally. The helicopter also would be capable of carrying a 10-person rescue gondola.
When I first started reading about this I assumed they would be using an Erickson Air-Crane which has already been developed and can carry about four times as much water.
These videos show the Erickson concept.