Isuzu is said to be extremely pretty, so much so that Nao and others have mistaken him for a girl. It is said that within their school, everybody considers Isuzu to be the 'flower' with just his exterior appearance. He is shorter than average height (for guys) and lacks the broad shoulders that most guys possess in this manga, in short, he is quite feminine looking. He has light coloured hair (not yet revelaed to be a certain colour) and skin that is 'soft, smooth and white'. While he and Karin are watching the sports teams some boys even go as far as to take pictures of him and one boy says that if it were a boys' school somebody would have made a move on him already. It is said by Nao's friend that Isuzu and Karin have a 'beautiful sisters' vibe about them.
Isuzu seems to be quite lazy, whiny and very very over protective of Karin (this may be due to the fact that he likes her and feels as though she is changing because of Nao).