I suppose it would be rare outside Japan but rare doesn't always mean valuable. Value is determined by demand and I don't see there being much demand for an import of a crappy Gameboy game. It might be kind of cool to buy just as a weird little novelty item but I wouldn't buy it specifically to sell it.

Looks rare to me. I think you should try to get more for that (of course, I suppose this is not a perfect game, but I also suppose its not shit).

That looks a lot like a pirate version of the game, the kind they used to sell cheap on market stalls. A lot of the time (not every case) they turn out to be shit, so buy it at your own risk. Or else try and haggle if you really must have it for your collection.

1&2 (US version) is not all that rare (GameGear MK3 is more rare). But if it is complete with the box, MK1&2 is the rarest portable MK game. Due to the possibility of a pirate cart, and me being low on funds, I cannot offer you anything for the game (I feel I got burned on a pirate GG MK1 a while ago). However, I would grately appreciate it if you could take some pics or scan the box/manual/cart for my website: PMK. You would recieve full credit. Thanks

Its no Pirate game thats for sure, MK1&2 (JP) is even in the official romset of Gameboy Roms.
The game is real.
But of course its nothing else than the normal MK1&2 but JP release, there isnt even japanese language in the game I think.
I think I buy it, maybe some fanatic collector will pay more someday =)

Not sure if I'm right, but this thread should go in Pocket Kombat Discussion.

Seems rare to me though, but remember that it could be a pirate.