* Topix rebounds after hitting 28-yr low on Monday
* Canon rises on share buyback plan; Sony regains 1,000 mark
* Fast Retailing sinks after weak Uniqlo same-store sales
* Olympus up, report of capital raising via share placement
By Sophie Knight
TOKYO, June 5 (Reuters) - Japan's Nikkei average sprang back on Tuesday from four straight sessions of losses as investors snapped up big name bargains ahead of emergency talks between the G7 industrialised nations to tackle a deepening euro zone crisis.
The Nikkei advanced 1 percent to 8,382.00, boosted by Canon Inc 's gain of 3.4 percent on plans to buy back up to $640 million worth of its own shares. The camera and printer maker was the top-weighted gainer and the most heavily traded stock on the main board by turnover.
"The market has calmed down from yesterday, but the atmosphere is still very much one of 'wait and see'," said Yasutaka Kuga, a partner at Senrigan Capital. "No one really wants to play their hands."
Leaders of the G7 industrialised nations were due to hold an emergency telephone conference later on Tuesday to discuss a deepening euro zone crisis as Spanish banks show increasing signs of strain and a June 17 Greek election poses the risk that the country may leave the euro zone.
"If nothing concrete comes out of the meeting then people will be disappointed," said Masayuki Otani, chief market analyst at Securities Japan. "But if they give a direction for how they're going to tackle the problems then the market might calm down."
Olympus Corp, which is struggling to recover from an accounting scandal, climbed 4 percent after the Sankei newspaper reported that it was considering raising about 50 billion yen ($640 million) through a third-party share allotment.
Although unease about the euro zone's fate remained, investors took the opportunity to pick up cheap stocks that were heavily knocked down on Monday on concern about a slowing U.S. economic recovery following a slew of soft economic data over the weekend and a sturdier yen.
Sony Corp climbed 3.3 percent to break back above 1,000 yen, glancing off a 32-year low, while Mazda Motor Corp bounced back 5.6 percent after tumbling 7.3 percent in the previous session.
Weighing on the Nikkei index was widely owned Fast Retailing Co Ltd, which lost 8.8 percent after reporting May same-store sales at its Uniqlo shops had dropped by about 10 percent.
The broader Topix index recovered on Tuesday to close up 1.8 percent at 708.24, gaining a foothold above 700 after breaching that level to hit a 28-year low on Monday.
"Today there is a short-covering rally going on," said Naomi Fink, equity strategist at Jefferies' Japan, who said that she remained long on volatility and short on securities and banks.
"There are still quite a lot of event risks, so I am not getting out of that vol (volatility) position anytime soon ... Factory orders were not as good as expected from the U.S ... I don't see that optimism coming out just yet," Fink said.
A report showing falling U.S. factory goods for the third time in four months added to a slew of soft U.S. data released since Friday that has renewed pessimism about a stuttering recovery in the world's largest economy.
Fears of a euro zone collapse and concerns about slowing growth in the United States and China have helped to push the benchmark Nikkei down 18.2 percent from its one-year peak on March 27.
Despite Tuesday's gains, the Nikkei was still in "oversold" territory, with its 14-day relative strength index at 29.3. Thirty or below is deemed oversold.
($1 = 78.4200 Japanese yen) (Additional reporting by Dominic Lau)