Charlotte Holmes A detective and criminologist who made a name for herself at a young age. Usually aloof and slovenly, she displays abnormal concentration when faced with a mystery. She has little interest in humans, but never overlooks an inexplicable case. She is on board this time as a pure tourist.

Arnold Frankenstein An arrogant baron who researches life itself. An unorthodox researcher who scoffs at existing theories and authority, he even used his own body as a test subject to reach immortality. In the process, he gained the power to manipulate electromagnetism. He is on board seeking the grimoire to be sold at the auction. He has a weakness for Darwin.

Machiavelli Fisher A mysterious strategist dressed in formal attire resembling a military uniform. Contrary to his serious appearance, he hides a playful side that enjoys the situation. Skilled in manipulation and statecraft, he was once deeply involved in the politics and military of a nation. He is on board to serve as the security commander at the auction venue.

Faust von Goethe An old mage who has spent many years researching magic and alchemy. Hedonistic and cynical, his wealth of knowledge stands out even among the passengers. He has made contracts with numerous monsters and spirits and has reached for research considered taboo. He is heading to the auction in search of the grimoire.

Leona Vinci A young magic engineer, painter, and inventor. A genius eccentric who observes, draws, and tries to understand the mechanism of anything that catches her eye. Never satisfied with existing technology, she is constantly creating new things. She is on board with Marie seeking the unknown knowledge to be sold at the auction.

Harland Turing A young train mechanic working for the Grimm Express. Taciturn and poor at socializing, he suddenly becomes talkative when the subject turns to machinery. Well-versed in the structure and control of magic machines, he handles the maintenance of this train single-handedly. After the anomaly occurs, he is the only one who faces the "train itself."

Marie Mercury A young magic chemist pursuing unknown magic substances. Calm and collected, she is indifferent to things outside her research, but shows hidden curiosity when faced with unknown phenomena. She rose to prominence at a young age in the study of magic substances and alchemy, and is on board with Leona seeking new knowledge at the auction.

Charlotte Darwin A naturalist who has traveled the world observing and studying living things. A gentle and quiet person, her eyes light up the moment she discovers an unknown creature or phenomenon. She has left behind vast specimens and observation records, building her own theories on the changes of life. She boarded for the auction but holds a strong interest in the anomalies within the train. She is an acquaintance of Frankenstein, and they get along poorly. She is always prickly in front of Frankenstein.