The Japanese RGB-21 connector, also known as EIAJ TTC-003 apparently, is identical in appearance to the European SCART (or Péritel or Euroconnector). The pinout is completely different however. There's an RGB← →SCART adaptor pinout here.
|17||Green shield||18||Blue shield|
This version includes every pin, including a few you'll never really need to know. All labels are display-relative, so input means into the display.
Most of these pins can be safely ignored for most purposes.
|1||Audio left channel input||2||Audio left channel output|
|3||Audio ground||4||Audio ground|
|5||Audio right channel input||6||Audio right channel output|
|7||Video ground||8||Video ground|
|9||CVBS input||10||CVBS output|
|11||AV control input||12||Ym input|
|13||Red signal ground||14||Ground|
|15||Red signal I/O||16||Ys input|
|17||Green signal ground||18||Blue signal ground|
|19||Green signal I/O||20||Blue signal I/O|
The detailed version was found on this Korean page