Fast-food lunches in Japan are starting to get cheaper as consumers look to trim their dining expenses, a worrying sign for the central bank as it tries to bring about inflation.

Japan's fast-food chains have lowered menu prices over the past six months, with McDonald's Japan, Burger King Japan and Yoshinoya Holdings Co. offering cheaper deals and lunchtime specials.

McDonald's rolled out a new weekday lunchtime combo set earlier this month, offering a burger and a small-sized drink for ¥400. The new menu follows an all-day, ¥200 burger promotion that the company introduced last October, says company spokeswoman Kokoro Toyama.