HONG KONG--(BUSINESS WIRE)--A.M. Best has affirmed the financial strength rating (FSR) of A+ (Superior) and the issuer credit rating (ICR) of “aa-” of Sompo Japan Nipponkoa Insurance Inc. (Sompo Japan Nipponkoa) (Japan). Concurrently, A.M. Best has affirmed the FSR of A+ (Superior) and the ICRs of “aa-” of Sompo Japan Insurance Company of America (SJA) and its reinsured affiliate, Sompo Japan Fire and Marine Insurance Company of America (SJFM), collectively known as Sompo Japan US Group (both d