TOKYO — The fervor is fading.

Prime Minister Shinzo Abe on Wednesday rolled out the next phase of his aggressive strategy to kick-start Japan’s economy, with plans to encourage foreign investment, nurture innovation and improve regulation. But almost immediately, a big question surfaced: Will they go far enough?

Since taking office in December, Mr. Abe has promised to fight deflation and spur growth through a combination of aggressive monetary easing, public works spending and economic overhauls. The initial efforts of his program showed promise, helping to drive the stock market up 80 percent from late last year.

But enthusiasm has waned in the last two weeks, as investors wondered whether the efforts were sustainable. The latest proposal did little to quell the concerns. The Nikkei 225-share index ended the day down 3.8 percent, another rout in an extended correction for the market.

In the next wave of so-called Abenomics, the prime minister laid out a wide range of policies aimed largely at the corporate sector. He plans to introduce tax breaks to increase foreign direct investment. He also said he would remove cumbersome regulations, for example in the medical industry, by removing a ban on sales of nonprescription drugs on the Internet. And he pledged to combine Japan’s high-grade infrastructure and manufacturing prowess with the daring and creativity of a younger generation.