It's just the normal Japanese version with a NTSC sticker on it. I"ve had a Thunder Force IV like that. Probably sold in Asian countries but carries the NTSC sticker to warn people that this game will only work on a NTSC Mega Drive (some Asian countries had both PAL & NTSC) due to the copy protection in the game. Take a look at my Japanese copy. It's 100% the identical. http://www.segagagadomain.com/megadrive2/bareknuckle3.htm
It is, ASSEmbler. I've owned a few in the past. Back in the 90's they were common in the UK probably due to the relationship we had with Hong Kong. Yakumo
WTF, why? It looks just like the Japanese version with a sticker on it. A sticker I didn't even notice until I read Yakumo mentioning it.
It's already complicated enough having two different manufacturing lines to produce a cartridge and packaging for the US and Japan, and then there's the whole multi-lingual problem of European distribution. Japan is the home market so its numbers don't matter, but the US and Europe (and for Sega, South America) outnumbered the Chinese, Hong Kong and Korean markets thirty-to-one, give or take. It didn't make sense at the time to have separate packaging and different cart circuit boards for the various Asian markets. It makes economic sense to me for an NTSC cart to get stuffed into a JPN package in that specific circumstance.