Izumi has silver-colored, chin-length hair, that covers both his ears and styled as one fringe. Izumi is noticeably short compared to his two friends, and dislikes being told that fact. He stands at 164 cm.
When he was younger, Izumi had shorter and more spikier hair.
Izumi is the more composed and calm member of Seiji's friends, being able to deduce the causes and reasons for the events that occur around him. Due to him constantly dating girls, he has reliable knowledge of them, and is better at understanding how to respond to a girl than anyone else.
Izumi is also quite secretive, never letting his personal life get involved with his school life, leaving his friends to know little about him and his problems. He is protective of those important to him, and when feeling that they need his help, he will spring to the rescue using his own, indirect, methods.
During the entire course of the series, Izumi plays a more supportive role, being a good source of advice for Seiji and a source of discipline for those who panic a lot. He is shown being popular with many girls, and also very good with many school subjects.
As the nearly emotionless member of Seiji's friends, Izumi is shown to always notice strange behaviors and expressions, especially on Yuki and Seiji himself. He dislikes getting too involved with other people's secrets, and will opt to do what he can to help those who are considered important.
As the smart and knowledgable member, Izumi does try to lend his friends the help they need, whether or not they really bother studying and instead singing. One day, Izumi catches Risa walking along with a dangerous type of guy, while dating a black-haired girl. Although he shows signs of lack of interest, he later uses his cell phone to record the man beginning to sexually assault Risa, and when things get too far, he uses his karate skills to apprehend him.
He later advises Risa to make the right decision, without being a pillar for her to support. Sometime later, he meets Risa again, and she thanks him.