By lunchtime, the index had risen 0,8 percent. The broader Topix index also increased, by 0,7 percent. The Japanese central bank is expected to keep the interest rate at 0,5 percent according to the analysts' assessment that Reuters reports on.
However, Shanghai's composite index falls 0,3, while Shenzhen's equivalent rises 0,1 percent.
Hong Kong's Hang Seng index climbs 0,2 percent on the week's last trading day.
