BoJ Trimmed Mean Core CPI y/y reflects a change in prices of goods and services from the consumer perspective, in the specified month compared to the same month of the previous year. Apart from excluding highly volatile product and energy prices, 10% of the consumer basket elements having the smallest changes in prices and 10% of those the highest change are also excluded to calculate the Trimmed Mean CPI.
Higher than expected readings are usually considered favorable for JPY quotes (since the BoJ can raise rates to fight inflation, which in turn can attract foreign investment). However in recession, the rise in CPI may lead to a more severe economic downturn and fall in the national currency.