ALTDEV ALT OVERSHOT IN CLB.

Narrative

OUR FLT; WITH THE FO FLYING; WAS CLRED FOR A PAPAS 1 DEP FROM NARITA ARPT (TOKYO) AND CLRED TO FL310. DURING CLBOUT TOKYO CTL ADVISED XING TFC AT 10000 FT AND 10 MI; THEN ADVISED CLR OF TFC AND SHORTLY AFTER ADVISED OF A SECOND ACFT AT 10000 FT AND 10 MI. WE WERE APPROX 9700 FT WHEN TOKYO CTL CLRED US TO CLB TO FL310 (ALREADY CLRED) ADVISED CLR OF TFC AND STATED THE WE WERE ONLY CLRED TO 9000 FT. WE HAD READ BACK THE TAS BUT DIDN'T ACKNOWLEDGE ANY ALT RESTRICTION BECAUSE WE DIDN'T RECEIVE ONE. THE CTLR WAS HARD TO UNDERSTAND BUT HE DIDN'T GET AN ACKNOWLEDGEMENT OF AN ALT RESTRICTION. CONTRIBUTING FACTORS: THE CTLR'S ACCENT; NOT RECEIVING (HEARING) THE ALLEGED RESTRICTION; AND NOT QUESTIONING OUR CLRNC WITH ACFT AT 10000 FT. THIS PROBLEM COULD HAVE BEEN AVOIDED BY THE CTLR ISSUING A RESTRICTION WHEN HE DIDN'T HEAR US ACCEPT A RESTRICTION WHILE ACKNOWLEDGING TFC. HE COULD HAVE ALSO CALLED US WHEN WE WENT THROUGH 9000 FT IF HE THOUGHT THAT WAS OUR CLRED ALT. WE SHOULD HAVE QUESTIONED OUR CLRNC. AT BUSY ARPTS LIKE NARITA AND O'HARE ETC; CTLRS DON'T GET READBACKS AND STILL ASSUME A CLRNC HAS BEEN RECEIVED.