Have you checked Japanese embassy's web site for work opportunities? I looked into working in Japan a while ago and I remember they needed Russian tutors. Also, maybe something in trade or travel business. After all, Russia and Japan are neighbours.
Also, where does your friend train in St.Petersburg? Lenkai dojo should have info on traveling to and living in Japan, I am sure a few people did it in the past. Or, you can try to contact St.Petersburg Aikikai through their web site www.aikido.spb.ru
Hope this helps
P.S. say hi to your friend, I used to train in Lenkai when I lived in Russia