Prominent Japanese musician Sakamoto Ryuichi, who is undergoing treatment for cancer, has published a video message ahead of the online streaming of his piano performances he recorded this autumn.

The message released on Wednesday shows Sakamoto sitting by the piano.

Japan's Chief Cabinet Secretary Kato Katsunobu has recorded a radio message for Japanese abductees in North Korea. He pledged that the government will spare no effort to bring them home as soon as possible.

Kato, who also serves as abductions issue minister, recorded the message on Monday. It will be aired by a group investigating the whereabouts of hundreds of missing people possibly abducted by North Korea.

Japanese carriers are offering users a function to register and check whether a person is safe.

Three major mobile phone carriers -- NTT Docomo, KDDI and Softbank -- are now operating the disaster message board.