Major airlines serving BOS–NRT routes in December include Japan Airlines (JAL), All Nippon Airways (ANA, via partner hubs), and U.S. carriers through codeshare partnerships. JAL and ANA are known for strong Japanese service levels, generous meal service on long-haul flights, and solid award availability with advance booking. U.S. carriers and alliances can offer competitive pricing and convenient connections via U.S. hubs. Compare seat pitch, in-flight entertainment, meal options, and baggage rules; premium cabin seats can be a worthwhile upgrade on long overnight transpacific segments. Use loyalty program mileage redemptions, alliance partners, and credit card benefits to offset cost. CTA: Compare December airline offers and redeem miles for available BOS to NRT upgrades.