Japan's Nikkei share average rose for a fifth straight day on Tuesday and scored another 15-year high after the yen weakened, while investors were cautious awaiting comments from US Federal Reserve Chair Janet Yellen later in the day. The Nikkei rose 0.7 per cent to 18,603.48 points, the highest point of the day and the highest close since April 2000. The broader Topix gained 0.4 per cent to 1,508.28, and the JPX-Nikkei Index 400 advanced 0.3 per cent to 13,680.93.