TOKYO—Japan’s exports and imports in December hit record highs in terms of their value in yen, data showed on Thursday, as supply bottlenecks eased at the end of 2021 amid rising prices. However, a persistent semiconductor shortage remained a headache for Japanese firms such as automaker Toyota, which slashed its near-term output target this week, in addition to uncertainties around the Omicron variant. “There’re considerable uncertainties” from Omicron, Takeshi Minami, chief economist at Norinchukin Research Institute said, adding it could derail various aspects of Japan’s economy from firms’ overseas supply chains to domestic consumption. Exports in December rose 17.5 percent from a year earlier, Ministry of Finance data showed, outstripping a 16.0 percent gain expected by economists in a Reuters poll but below a 20.5 percent rise in November. Yen-denominated exports and imports hit records of 7,881.4 billion yen ($69 billion) and 8,463.8 billion yen, respectively, biggest since comparable data …