The helicopter drop was made from 300 meters altitude because of the radiation hazard. In the NHK video, relatively little of the water appears to have actually hit the target reactor. It appears to have dispersed too much during the long drop. I am wondering if they could extend a series of hoses several hundred feet from the chopper and dump the water through those to improve the accuracy.
These helicopters are Boeing CH-47s, License-built in Japan by Kawasaki. There are 54 of these in the Ground SDF (the army) and another 15 in the Air SDF. The Maritime SDF (navy) has 10 of the larger CH-53Es but I haven’t seen this used in this operation yet.