"They come from Japan."
Translation:Mereka berasal dari Jepang.
mereka dari Jepang should be correct also?
Yes, that has more or less the same meaning, "they are from Japan".
I think (I'm not sure) that this sentence is from the skill "ber-verb".
That's probably the reason that "berasal" is used here.
asal (noun) = origin
berasal (verb) = to originate from, to come from.