The fiscal year ending March 2015 is looking less rosy for Japanese automakers, who are unlikely to benefit any further from the weakened yen because of fierce overseas competition, experts say.

Profit growth at Toyota Motor Corp., Honda Motor Co. and Nissan Motor. Co. will likely slow this year, said Takaki Nakanishi, CEO of Nakanishi Research Institute.

In the year ending March 31, Toyota posted a record group operating profit of ¥2.29 trillion, jumping 73.5 percent from the year before. But this year the auto giant expects a mere 0.3 percent increase in operating profit to ¥2.3 trillion.