is a Japanese former windsurfer, who specialized in the class. She was the country's top female windsurfer for the 2008 Summer Olympics, finishing in thirteenth place. A member of Toyama Sailing Federation, Kosuge trained most of her competitive sporting career for the national team.
Kosuge competed for the Japanese sailing squad, as a 34-year-old, in the inaugural class at the 2008 Summer Olympics in Beijing. She topped the selection criteria in a duel against the quota recipient Yuki Sunaga for the country's RS:X berth, based on her cumulative scores in a series of international regattas approved by the Japan Sailing Federation. Kosuge enjoyed the initial half of the series with a couple of top ten marks recorded, before fading temporarily towards the middle of the fleet. She made a late surge to finish seventh on the final leg but fell short to enter the medal race by the narrowest margin, sitting her in thirteenth overall with 102 net points.