Max O'Donald Maccallister is a cyborg who formerly served in the space military before working for a security services company that handles legally ambiguous jobs. He and his partner Kurt Cramer were arrested for smuggling illegal sugar and sentenced to community service cleaning the interplanetary train known as the Milky Subway as part of a prison-overcrowding reduction program. Max is characterized by a conspicuously flat, monitor-like face with only two dots for eyes, a detail that makes his expressions difficult to read. He is often seen fussing over his blond hair and tends to be indifferent toward others, spending most of his free time playing handheld games. His personality comes across as lighthearted and flippant on the surface, but this demeanor masks a deeper disillusionment. Before becoming a cyborg, Max was a vain young man who feared the effects of aging. A military recruiter convinced him that enlisting would grant him free cybernetic surgery to preserve his youthful appearance. However, after the operation, his face was completely replaced by a mechanical display, exactly what he had hoped to avoid. He later grew tired of the harsh training and left the military. In the civilian workforce, he felt treated like a machine rather than a person and was never thanked for his efforts, which led him to become cynical and to seek work in the gray economy. Max’s primary motivation throughout the story is self-interest and financial gain, but his actions also reveal a hidden desire for recognition. He is highly skilled in information processing, memory retrieval, and gadget operation, often using hacking devices to bypass security systems. In the narrative, Max and Kurt initially refuse to help the other convicts without payment, but when the protagonist Chiharu sincerely thanks them after they disable a security robot, Max is visibly caught off guard and decides to forfeit the remaining fee. This moment marks a turning point in his character development, as it reconnects him with the appreciation he once lacked. His relationship with Kurt is that of a close partner; they bicker and play games together but rely on each other’s complementary abilities—Kurt’s physical strength and Max’s technical expertise. Over the course of the incident aboard the runaway train, Max gradually moves from detached indifference to a modest willingness to cooperate with the group, though he retains his dry, teasing manner of speaking.