is a high school student with a charismatic and helpful nature, he lives with his mother who has separated from his father due to marriage problems. He has two close friends, Haru and Furuichi. After a suicide bomber from the religious cult of Ruikonism detonates herself on his school bus, releasing the seven beings in a green egg inside her, they fly off as bright pulsing lights one of which lands on Akiyuki's arm, absorbs itself under his skin, and materialises as a blue gem-like object on his right biceps. As the bomber is dying, she touches his forehead, making first a small red gem appear, then a white and green mask. Within moments, Akiyuki's entire body transforms into an exotic white creature and engages in battle with a humanform weapon which attacked the area around the bus shortly after the bombing. Following his successful defeat of the humanform weapon, Akiyuki is subdued by a mysterious woman named Nakiami, who threatens to let him turn to stone if he does not go with her to the airship Zanbani where he must learn to coexist with the being within him. The blue gem-like object on Akiyuki's body, which has now moved to his forearm, is later revealed to be manifested appendage of an endosymbiotic organism referred to within the show as a "hiruko". When a hiruko endosymbiont merges with a human, the resulting combined life form is referred to as a "Xam'd".
Atsushi Abe (Japanese), Blake Shepard (English)