Hongo began her season by winning both segments in a domestic competition called the Summer Cup, held in Shiga prefecture, Japan. Two months later, she outscored Yulia Lipnitskaya by 15.12 points to win gold at a Challenger Series event, the 2015 CS Finlandia Trophy, where she obtained a personal best total score of 187.45 points. Hongo then won silver at 2015 Cup of China, but placed fifth at 2015 Rostelecom Cup, and as a result, did not qualify for the Grand Prix Final. She placed 4th at the Japan Championships.