Something missing from the history books: Sega were all set to distribute the ColecoVision in Japan: https://retrocdn.net/index.php?title=File%3ACashBox_US_1982-04-03.pdf&page=62 I don't think a Japanese ColecoVision ever existed. But you know what did exist? The SG-1000. This announcement came in April-ish 1982, but the SG-1000 didn't launch until July 1983. Plenty of time to put together a ColecoVision plan, decide that it sucks, copy some of the technology and produce your own console (and computer... and then upgrade it down the line with the Master System and Mega Drive). Freaky deaky.
Nice find! Yeah, SG-1000 is basically a ColecoVision clone. As it used off the shelf components then there was little to stop Sega from largely copying it. Incidentally, Coleco released the Gemini in 1983, a clone of the Atari 2600. Trying to find the first Sega game to get a home release, it seems to have been Zaxxon and/or Carnival for the ColecoVision in October 1982, followed by Turbo in November 1982. The funny thing was, when Sega started to release games for Western platforms themselves in 1983, they couldn't release them on ColecoVision as Coleco had the license.
