This is significant news. According to the Japan Times...
The Lower House, by a 263-167 vote Thursday, passed a bill to (1) recognize brain death as actual death and (2) allow organ transplants from a brain-dead person of any age if his or her family members approve and if the person had not openly rejected the possibility of becoming a donor.
The bill would revise the 1997 Organ Transplant Law, which allows organ donations from a brain-dead person at least 15 years old only if that person had indicated his or her intention of becoming a donor in writing, such as on a donor's card, and if his or her family members approve the organ donation.
One of the big issues surrounding organ donation in Asian countries is the consensus that brain death is not actually death. Add to that the idea of making the body impure by removing what is naturally there (applies to accepting organs as well), and you have an idea of the current Japanese policy: many go to China to accept less-than-reputable transplant procedures from prisoners, as Kenichiro Hokamura did in March 2006. The only other option available to those in need up to this point had been to legally join the UNOS list in the US, which could take months or years to receive an organ.
I have no idea what prompted this sudden change in policy, but it's especially good news for sick kids under the age of 15.