Nhk

[David Roper]

Here's a Japanese prototype set from 1955:

Trial manufacture of color television receiver of NTSC system (1955)

3 color picture tubes 15GP22 (15 inches) the color television receiver which is used was made on an experimental basis in 1925. [sic] As for this television receiver other than the picture tube, the high pressure stable tube and the delay line being something by the domestic part, it was the color television receiver of new NTSC system in our country.

[reeferman]

For what it is worth, here is a lift from Toshiba's view on color development in Japan

http://museum.toshiba.co.jp/history/1goki/1958tv.html