Nikkei rises to fresh 15-year high as Greece debt deal looks more likely
* Nikkei inch away to hit 18-year high * Banks higher on their attractive valuations - trader * Toshiba underperforms after report saying accounting trouble spread to other ops By Ayai Tomisawa TOKYO, June 23 (Reuters) - Japan's Nikkei share average rose to a fresh 15-year high on Tuesday morning as hopes grew that a deal would be reached to avoid Greece defaulting on loans, lifting recently fallen stocks such as banks. The Nikkei share average was up 1.4 percent at 20,715.5