This news is not specific to Kumamoto but I suspect there are quite a few people here who will be pleased by the change.
http://newsonjapan.com/html/newsdesk/article/110076.php
SIM locks on handsets to be removed in Japan next summer
The Japanese communications ministry is in the final preparations to urge mobile carriers to remove subscriber identity module locks from mobile phones in the summer 2015, a step to allow users to choose their own service providers, sources said Tuesday.