Akiyuki is an arrogant teenager with seperated parents living on Sentan island, a small island that is a neutral zone in a war between the Northern and southern governments. While Akiyuki was riding a bus to his high school, he meets a mysterious pale girl who causes the school bus to deonate. After the explosion, a mysterious light appears and enters Akiyuki's body. After coming to the girl's aid, she touches his forehead causing a small gem to appear, creating an organic, white mask. Soon after Akiyuki transforms into an extremely powerful creature called Xam'd.
Akiyuki is somewhat arrogant and very stubborn in the beginning of the anime but sometimes remorseful for his actions and after training with Nakiami, he becomes kinder and grateful for Nakiami's Mercy. While in his xam'd form he can be violent, relentless and silent.