福山潤
is the black belt leader of Jindai High's Karate Club. However, he is extremely nearsighted and can see clearly only when wearing his glasses, which leads to several comic incidents. His sense of pride cannot accept the fact that he was defeated by Sousuke and is constantly challenging him to rematches, which Sousuke usually avoids. He has a huge crush on Kaname and in the short story "Irrelevant Emotion" accidentally indicates Sousuke when confessing his love for her. In the "Full Metal Panic? Fumoffu" anime, Mizuki falls in love with him in the last episode. In "Irrelevant Emotion", however, she falls for him after he saves her from falling out of a window. He is voiced by Jun Fukuyama in the original Japanese anime, by Nomed Kaerf in the English version by ADV Films.