there is no reason for a region lock. the only game that has it, did it to prevent japanese people from importing cheap NA copies of the game, since there is only one version.
and the best thing is, that the japanese don't care enough about eruope to even change in 20 seconds worth the region-code and send out the master disk to a publisher over here. so we can't buy it here, and we can't import the game due to the region lock. game was released over 3 months ago... the loss of sales they have here due to their behavior will cost them vastly more money, then the few bucks they'd lose from the 10 people importing the game from NA in japan. smart move Atlus JP, smart move.