TOKYO, Jan 27 (Reuters) - Japan's Nikkei average tumbled to a two-month low on Monday as the yen soared and global equities dropped on concerns about a selloff in emerging-market assets, dragging down futures and index-heavyweight stocks. The Nikkei ended 2.5 percent lower at 15,005.73, the lowest closing level since Nov. 14. It fell as much as 3 percent earlier. The Topix fell 2.8 percent to 1,229.23, with all of its 33 subsectors in negative territory. Volume was high, with 3.265 billion shares changing hands, the highest since Jan. 10. The JPX-Nikkei Index 400, a recently introduced gauge comprised of firms with high return on equity and strong corporate governance, dropped 2.8 percent to 11,103.87.