In the Japanese version, he is voiced by Kenichi Suzumura in TV series and Tomokazu Seki in movie.
In the English version, he is voiced by Steve Staley in TV series and Alan Marriott in movie.
Kamui is a rather short, slim young man. During his time in high school, he is referred to as an attractive person, being quite popular with the girls on just his first day, a fact that he was oblivious and/or apathetic to. His skin is pale, almost white, and has big blue eyes (which can sometimes be considered violet and in "X the Movie" appear to be golden brown) slightly covered by his spiky, rather long, deep-black hair. On many pictures in artbooks he has brown hair. His usual outfit is the uniform of his school, a black gakuran with red outlines and golden buttons and a white shirt underneath. Representing his role as a potential Dragon of Heaven or Earth, he is sometimes shown with a white angelical wing in his right shoulder, and a black demonic wing on the left; there's been also representation of him wielding both white or both black wings, sometimes holding a globe of the world.
As a child, Kamui was kind, innocent, quite bashful and quiet, but also reliable, as seen when he protected Kotori, fulfilling his promise with Fuma. After his departure from Tokyo, his personality in Okinawa was slightly changed; he remained quiet but when angry, he developed his psychic powers with anger and sorrow; but was still very protective with the ones he loved. After the death of his mother and the discovering of his fate, once he returned to Tokyo, Kamui became cold, stoic and distant with Kotori and Fuma. He was also reckless and rash in his behavior, as seen when he tried to steal the Sacred Sword from the Monou Shrine, severely injuring Kyōgo Monou, its guardian. Upon meeting Sorata Arisugawa and Princess Hinoto, he was reluctant and refused to be involved with the end of the world crisis. After a while, he started to open with Fuma and Kotori, which led to him deciding to become a Dragon of Heaven to protect the siblings, but with this decision, Fuma became his twin star as a Dragon of Earth, thus turning Fuma into a savage and violent person, killing his sister and breaking Kamui's heart. Though this was painful to him, he became closer to his fellow Seven Seals, specially with Sorata who always was by his side, Subaru Sumeragi, who risked his own life to rescue him from the catatonia caused by Kotori's death, Yuzuriha Nekoi because of her gleeful and energetic personality, and with the serious and reliable Arashi Kishuu, and never forgetting his mission to rescue Fuma and to turn him into his prior self.
- He have alternate version of himself, Kamui from Tsubasa: Reservoir Chronicle.
- His English Voice Actor, Steve Staley is best known voicing as Ryo Akiyama from Digimon Tamers, Koji Minamoto Digimon Frontier, Tōshirō Hitsugaya from Bleach and Neji Hyūga from Naruto/Naruto Shippuden.