TOKYO, May 2 (Reuters) - Japan's Nikkei share average gained a modest 0.3 percent on Wednesday, buoyed by an easing yen after U.S. manufacturing data beat expectations, but investors were restrained ahead of two market holidays and European elections at the weekend. The Nikkei rose to 9,380.25, while the broader Topix index advanced 0.4 percent to 792.87.