TOKYO—Consumer inflation in Tokyo will likely post slightly slower year-on-year growth in January, a Reuters poll showed, after the suspension of a government discount travel campaign in late 2020 led to a less favorable situation for price rises. Still, core consumer prices in the capital city—widely considered a leading indicator of nationwide price trends—likely stayed in positive territory for a fifth consecutive month, even when stripping out the boost they got from 2020’s low comparison base brought about by discount travel offers. Tokyo’s core consumer price index (CPI), which includes energy but excludes fresh food prices, was expected to rise 0.3 percent year-on-year in January, the poll of 16 economists showed. That would mark the slowest growth in the core CPI of Japan’s capital since a 0.3 percent gain in November. “While energy and food prices likely accelerated further as rising import costs are passed on, the gains will be …