Takata Corp. is bracing for further defections after Honda Motor Co., its top customer, began turning its back on the distressed Japanese air bag maker.

Mazda Motor Corp. said on Thursday its new cars will no longer use Takata air bag inflators linked to scores of injuries and seven deaths in the U.S., while Subaru-maker Fuji Heavy Industries Ltd. and Mitsubishi Motors Corp. are considering the same.

The comments follow Honda's decision to stop using Takata inflators in new models and its accusation that the company manipulated test data, triggering a record two-day, 35 percent, rout for Takata's shares.

The emerging rifts mark an unusual repudiation in Japan, where corporate relationships are measured in decades and Takata had counted on automakers' support despite more than a year of criticism from U.S. lawmakers and its auto safety regulator. Even investors appeared to think the worst was over, with the stock up 14 percent this year through May.

The tide turned this week when Honda surprised the market and set the stage for a potential exodus of more customers.

"I don't remember ever seeing anything like this in the auto industry, where automakers dump their supplier one after another," said Koji Endo, an analyst at Advanced Research Japan who's covered the sector for more than 30 years. "Safety devices are the most important parts used in cars. Honda, Mitsubishi, Subaru might have thought they can't continue buying such important parts from a company like this."

Takata, which reports earnings on Friday, plunged by the daily limit in Tokyo trading on Thursday, sinking 25 percent to ¥889. Spokesman Toyohiro Hishikawa declined to comment for this story.

At least two of Takata's largest customers are sticking with its air-bag inflators for now. Toyota Motor Corp., the carmaker with the second-most vehicles involved in the recalls after Honda, is still investigating the root cause of the inflator issues, Senior Managing Officer Shigeru Hayakawa said Thursday. Nissan Motor Co. said Wednesday it was "surprised and disappointed" by NHTSA's findings and deferred to NHTSA to take action.

Honda's desertion was significant as it led analysts to openly question Takata's ability to survive and even President Shigehisa Takada acknowledged a risk to the company's existence. Asked whether the company will survive, 49-year-old Takada told reporters Wednesday, "there's risk."

Any blows to Takata's air bag business are devastating because it's the company's largest product segment, at 38 percent of its ¥642.8 billion ($5.3 billion) in sales for the fiscal year ending in March. Inflators are only a portion of its air bag products, and other components the company has to fall back on include seat belts, steering wheels, electronics and child seats.

Honda made its announcement hours after the U.S. National Highway Traffic Safety Administration fined Takata a record $200 million. The agency ordered the company to phase out ammonium nitrate-based inflators, linked to seven deaths and almost 100 injuries in the U.S., by 2018. NHTSA also said Takata provided "selective, incomplete or inaccurate information" to the agency and customers since at least 2009.

"For years, Takata has built and sold defective products, refused to acknowledge the defect, and failed to provide full information to NHTSA, its customers, or the public," Transportation Secretary Anthony Foxx said in a statement. "The result of that delay and denial has harmed scores of consumers and caused the largest, most complex safety recall in history."

The moves by Honda and Mazda add to a shift away from Takata that was already taking place involving the use of the replacement inflators for recalled vehicles. By March, Daicel Corp., Autoliv Inc. and TRW Automotive will make about 68 percent of those components, according to a letter Takata sent to NHTSA in July.

Honda, which has bought parts from the supplier for more than 50 years, said this week it will be able to source all replacement inflators from suppliers other than Takata in the foreseeable future. The carmaker will be buying the substitute components from all three of Takata's competitors.