Consumer prices in Tokyo, a leading indicator of nationwide inflation, rose 2.8 per cent in September from a year earlier in the year, marking the biggest gain since 2014 in a sign of a wider cost pressure.
The consumer price index for Japan's capital, which includes oil products but excludes fresh food prices, matched a median market forecast and followed a 2.6 per cent gain in August.
It was the fourth month that the index's rate of increase exceeded the Bank of Japan's 2 per cent target, and beat a 2.8 per cent gain in June 2014.
The government data shows that more firms are passing on rising raw material costs to households, as well as a wide range of goods and services, such as electricity bills, chocolate, sushi and hotel bills.
The data is one of the factors that the BOJ will look at in order to gauge whether recent cost-push inflation could lead to a sustained rise in prices driven by robust domestic demand.
The BOJ has pledged to keep monetary policy ultra-loose despite recent rises in inflation, which it sees as driven by temporary factors like higher fuel and raw material rather than strong consumption.