Tokyo stocks fell 0.02 percent in the morning session of Tuesday as market sentiment was sapped by Moody 's Investors Service Inc.'s downgrading of Japan's sovereign debt rating the previous day.
The 225-issue Nikkei Stock Average was down 3.86 points, from Monday to end the morning session at 17,586.24.
The broader Topix index of all First Section issues on the Tokyo Stock Exchange lost 0.29 point, or 0.02 percent, at 1,421.36.
Decliners were led by foods, real estate and other manufacturing issues, while mining as well as oil and coal products gained footing.