Main characters ; : :The protagonist of the series. A diver of the Metal and longtime friend of Eiichiro Kushima. Masamichi was in a diving accident while testing an early Meta-Real technology, and was in a coma for 50 years before awakening as a paraplegic old man. Since the incident, he began searching for the "answer in the sea". Towards the end of the series, he eventually regains his ability to walk. ; : :An intern hired by Masamichi Haru and sister of Souta Aoi. Originally hired to replace Holon during a leave for maintenance, she became a permanent employee after she helped guide Masamichi back from a dive gone wrong. Unlike the other humans and some animals in the story, she does not possess a Cyberbrain augmentation, and requires electronic accessories to access the Metal. ; : :Employee of the EISF and brother of Minamo Aoi. He begins to have feelings for Holon towards the end of the series. ; : :A
Gynoid who helps Masamichi Haru with daily life in his old age and assists him in his search for the "answer in the sea". ; : :The director of the Electronics Industry Physical and Chemical Research Institute and friend of Masamichi Haru. While as old as Masamichi, his body has the appearance of a 28-year-old man. It was revealed later in the series that Kushima chose to replace his original body with a prosthetic one, allowing him to continue his work beyond the limits allowed by the human body. He has a spare body to which he transfers his consciousness during his usual body's maintenance, one which might be modeled after the young Haru (Minamo remarked in episode 20 that his spare's appearance reminded her of Haru in his youth).
Supporting characters ; : :The Chairwoman and First Princess of Artificial Island, Secretary General of the Council, and Souta's love interest. It is later revealed that Holon is modeled after her. ; : :The Chairman of the Council's Advisory Committee. Like Kushima, he, too, has a prosthetic body, but it has been upgraded for military use and is armed with a
stun gun. ; : :The father of the Aoi siblings and chief of the Technical Section in the Department of Management at Denriken. Following an incident that occurred when the Metal crashed in episode 9, he resigns from his post and works as one of the lab researchers.
Other characters ; : :Androids employed at Denriken who control and monitor the Divers' status, as well as sudden changes within the Metal. Like Holon, they all take the same appearance as Takanami. ; : ; : ; : :Souta and Minamo's mother. ; : :Souta and Minamo's grandmother. ; : :Minamo's classmate. ; : :Minamo's classmate. ==Media==