From the link above:
http://www.panasonic.eu it states:
Product:
"The K21-10, National's 21-inch diagonal colour TV, was the company's first ever colour television. Featuring unique 21-inch three-colour CRT's, six different types of vacuum tubes, and highly advanced circuits offering outstanding performance, the K21-10 was a great leap forward in colour TV.
Inspiration:
The K21-10, a first for Panasonic, was developed to coincide with another groundbreaking first in Japan - the start of colour television broadcasting. In developing it, the company established new technology for mass-producing colour cathode ray tubes and colour television receivers.
Context:
On September 10, 1960, five commercial stations began colour television broadcasts in Tokyo and Osaka, marking the dawn of colour TV in Japan. Working alongside the Japanese Broadcasting Corporation, Matsushita developed its first ever colour TV.