Terushima is shown to be childish and extremely energetic. He's not one to take things seriously, as he even dismissed volleyball as something played for fun and didn't put much thought into the sport as he thought it wouldn't be as enjoyable. However, he has a change of heart after the match against Karasuno, realizing that playing seriously and winning gives much more satisfaction. He was shown being rather assertive and persistent as he approached Kiyoko before the Karasuno vs Johzenji match.