<sod >The mother of a Japanese hostage held by Isis extremists has made an emotional appeal to prime minister Shinzo Abe to save her son after his captors issued what they said was a final death threat.< eod>< sod > The mother of a Japanese hostage being hold hostage by Isis militants has made a second emotional appeal to Prime Minister Shinzo Abe to save her son after his captors threatened to kill him within 24 hours.< eod>