"There is a popular view in the market that Japanese companies will get a huge boost from this foreign-exchange factor, especially in fiscal 2013," said Hiroichi Nishi, assistant general manager of equity research at SMBC Nikko Securities Inc.
"Things may get even better for Tokyo stocks if the United States can avert the fiscal cliff and Wall Street stocks rebound strongly," Nishi said.
Japan's Nikkei 225 index closed at 10,395.18 Friday, its highest mark since March 10, 2011, the day before a massive earthquake struck with the epicenter in Northeast Japan, Kyodo News reported.
The weaker yen benefits Japanese exporters, as it helps make their prices more competitive abroad. While exporting firms gained with a four-day winning streak through Friday, utility firms, drug companies and airlines did not fare so well.
The yen has been falling, with the expectation that the new government led by Prime Minister Shinzo Abe will aggressively deploy monetary easing strategies to stimulate the economy.
The Nikkei 225 closed out the year at its highest point for the year for the first time since 1999.