What is "ntsc-j"

NTSC-J is the discontinued analog television system and video display standard for the region of Japan that ceased operations in 44 of the country's 47 prefectures on July 24, 2011. Analog broadcasting ended on March 31, 2012 in the three prefectures devastated by the 2011 Tohoku earthquake ( Iwate, Miyagi, Fukushima).

While NTSC-M is an official standard, "J" is more a colloquial indicator as used in Marketing definition (below) but not an official term.