Why are food and drink prices in Japan set to rise as early as this summer, according to the news?

Food and drink prices in Japan are set to rise as early as this summer due to a war-driven shortage of naphtha — a critical petrochemical feedstock used to produce polypropylene and polyethylene plastic packaging — caused by prolonged disruption to energy flows via the Strait of Hormuz; this shortage has prompted packaging suppliers to demand higher prices with immediate effect, particularly impacting small and mid-sized food manufacturers.

Which food category is highlighted as especially vulnerable to price increases in Japan through September, and what broader inflation trends does the report cite?

Confectionery, including chocolate, is highlighted as among the categories most likely to be affected by price increases through September. The report also cites that Japan’s core consumer prices (excluding fresh food) rose 1.8% year-on-year in March — above both the prior month’s 1.6% advance and the median economist estimate — while the BOJ’s preferred measure (excluding fresh food and energy) increased 2.4%, remaining above the central bank’s 2% target; overall inflation including all items accelerated to 1.5%.