JPX-Nikkei 400 futures debut amid growing ROE interest

* JPX-Nikkei 400 hits 70,000 futures contracts * New index futures could outperform Nikkei, Topix - analyst By Ayai Tomisawa TOKYO, Nov 25 (Reuters) - The Osaka Exchange started trading of the JPX-Nikkei Index 400 futures on Tuesday amid increasing interest from foreign investors seeking long-term investment in companies with a relatively high return on equity. The new JPX-Nikkei Index 400 futures is based on the JPX-Nikkei Index 400, a benchmark introduced this year comprising