Do you get the impression that Japan has numerous benevolent and talented researchers who could and would contribute meaningfully to AI safety work? If so, it seems possible to me that your comparative advantage is in evangelism rather than research (subject to the constraint that you're staying in Japan indefinitely). If you're able to send multiple qualified Japanese researchers west, that's potentially more than you'd be able to do as an individual.

You'd still want to have thorough knowledge of the issues yourself, if only to convince Japanese researchers that the problems were interesting.