Tokyo stocks surged 2.20 percent at the close Thursday after the Bank of Japan unveiled fresh easing measures, reversing a heavy drop earlier in the day.
The benchmark Nikkei 225 index gained 272.34 points to 12,634.54, while the Topix index of all first-section shares rose 2.70 percent, or 27.33 points, to 1,037.76.
In volatile trade, the Nikkei's close was more than 558 points above the day's low, a turnaround that largely came after the central bank chief's announcement of easing, which sent the yen plunging.
The Nikkei had opened 1.4 percent down from the previous day's close and fell further to 12,075.97 in the morning.
The closely watched announcement came after the central bank's first policy meeting under a new leader who has vowed to turn around the stuttering economy.
It was welcomed as a "positive surprise" by investors, who had been concerned new governor Haruhiko Kuroda would fall short of expectations after promising to reverse decades of deflation and limp growth.
After a two-day meeting the central bank said it would embark on an aggressive spending programme, boosting asset purchases including Japanese government bonds, while pledging to meet a two percent inflation target within two years.
The moves would see the BoJ "enter a new phase of monetary easing both in terms of quantity and quality", it said in statement.