Kaito Yashio (八汐 海翔 Yashio Kaito?)
Voiced by: Ryohei Kimura (Japanese), Clifford Chapin (English)
The protagonist who constantly plays the fighting game Kill-Ballad and is a member of his school's robotics club. After the Anemone-gou Incident he suffers from spasms in which time seems to be moving extremely slow for him. He is not interested in robots, and is only a member of the club to be by Akiho's side, as Misaki left her to him before she left the island.
Akiho Senomiya (瀬乃宮 あき穂 Senomiya Akiho?)
Voiced by: Yoshino Nanjō (Japanese), Lindsay Seidel (English)
The main heroine and the only other member and chairman of the robotics club at the beginning. After the Anemone-gou Incident she suffers from spasms in which time seems to be moving extremely fast for her. Her dream is to complete the giant robot Gan-tsuku started by Misaki.
Subaru Hidaka (日高 昴 Hidaka Subaru?) / Mr. Pleiades (ミスター・プレアデス Misutā Pureadesu?)
Voiced by: Yoshimasa Hosoya (Japanese), Jarrod Greene (English)
A second-year student in the same school as Kaito and Akiho. He won the Robo-One championship several years ago and as a result Akiho tries to get him to join the robotics club, but he refuses because his father got him to promise he'd stop playing with robots in high school and become a fisherman after graduating. Kaito blackmails him into joining the club with Mr. Pleiades' identity.