Asian markets fell on Monday after a better-than-expected rise in US job creation fuelled concerns the Federal Reserve will soon start to reel in its huge stimulus programme.
Tokyo's benchmark Nikkei index sank 1.40 percent, or 200.63 points, to 14,109.34 despite the weakening yen, as a ratings agency downgraded Softbank to junk following its multi-billion-dollar acquisition of Sprint Nextel.
Ratings agency Standard & Poor's downgraded Softbank two notches to BB+ after it bought US-based Sprint Nextel, which in turn dragged on the Nikkei, while losses in Chinese shares also fuelled selling, analysts said.
"The rating cut was clearly deeper than expected, and it took SoftBank to well under investment grade," Monex market analyst Toshiyuki Kanayama told Dow Jones Newswires.
"But the selling may only be limited to today, or at worst, a few days, since the firm's big takeover deal has now been given regulatory approval.
"Investors believe in the company and have faith in its management, including (company head Masayoshi) Son, to grow the company. Shares have been bid up to the point where players were almost looking for an excuse to sell them down."
SoftBank ended down 3.4 percent at 5,680 yen, falling immediately after S&P's midday cut of its long-term credit rating from BBB to BB+, citing its Sprint Nextel acquisition, the largest M&A deal in Japanese corporate history.
The greenback slid against the Japanese unit to 100.99 yen in Tokyo afternoon trade from 101.14 late Friday in New York.
Japan introduced new nuclear safety regulations on Monday, with utilities asking authorities for permission to restart reactors.
Four utilities have submitted applications for the re-firing of 10 nuclear reactors in five plants, their first such requests since the Fukushima disaster two years ago.
However, Tokyo Electric Power Co, which made no submission, rose 4.31 percent to 628 yen, but Kansai Electric Power Co, who asked the watchdog to look at four of its reactors, was down 1.74 percent at 1,404.
The Seoul index slipped 0.90 percent, or 16.46 points, to 1,816.85 and Sydney gave up 0.67 percent, or 32.3 points, to 4,809.5.
Hong Kong fell 1.31 percent, or 272.48 points, to 20,582.19 while Shanghai lost 2.44 percent, or 48.93 points, to end at 1,958.27.
The euro, which came under pressure last week after the European Central Bank said it would keep rates at record lows for "as long as necessary", bought $1.2835, compared with $1.2832 late Friday. It was also at 129.85 yen from 129.78 yen.
In Seoul Asiana Airlines fell 5.76 percent after one of its planes crashed while landing in San Francisco at the weekend, killing two passengers and injuring 182 more.
Oil prices slipped. New York's main contract, light sweet crude for delivery in August, fell 12 cents to $103.10 a barrel and Brent North Sea crude for August lost 39 cents to $107.33.
Gold was at $1,226.10 per ounce at 0805 GMT, compared with $1,239.70 late Friday.
In other markets:
-- Taipei fell 1.44 percent, or 115.48 points, to 7,886.34.
Taiwan Semiconductor Manufacturing Co. shed 3.67 percent to Tw$105.0 while smartphone maker HTC tumbled 7.0 percent to Tw$189.0.
-- Manila tumbled 2.79 percent, or 181.57 points, to 6,318.91.
Ayala Land fell 3.17 percent to 29 pesos while SM Investments dropped 4.38 percent to 851 pesos.
-- Wellington was flat, edging up 3.43 points to 4,493.30.
Chorus added 0.76 percent to NZ$2.65 and Contact Energy rose 2.47 percent to NZ$5.40 but Fletcher Building was off 2.2 percent at NZ$8.43.