HONG KONG, May 28 (Reuters) - Fidelity International's China head James Sun has left the firm, the asset manager said on Thursday, after serving in the top job for about a year. Sun, a China fund veteran who was appointed general manager to lead the Britain-based firm's China fund management firm last May, left for "personal reasons," Fidelity's Asia ex-Japan head Damien Mooney told staff, two sources with knowledge of the matter told Reuters. Sign up here.