By Tom Westbrook SINGAPORE (Reuters) -Japanese markets were reeling on Friday, with the Nikkei heading for its biggest weekly drop in a year while bonds have been battered and the yen is eyeing its largest weekly gain in five months, as investors rushed out of bets on Japan’s rates staying low. Beyond Japan, the MSCI’s broadest index of Asia-Pacific shares ex-Japan bounced 0.8% and Treasuries were sold down slightly. The Nikkei was down 1.8% on the day, for a weekly drop of 3.6%, with exporters such as automakers falling hardest. [.T] Other moves were more modest as traders waited on U.S. labo…