Remulo grew up in a small town with his sister and parents, besides them he had someone else, Sombra, a living shadow, being a characteristic of his family. Most people regarded her as an imaginary friend however, as whenever there was another person around she would disguise herself as a normal shadow. This didn't contribute much to his reputation at school, he hardly had any friends and being kind of nerdy and weird he ended up becoming a target for some bullies, and even though he could fight back he usually didn't do it because he didn't like violence or confrontations.

Her shadow didn't quite agree with his actions and as Remulo was slowly realizing she became more and more manipulative, reaching the point where she started to take control turning him into a monster. This scared him and he started to avoid places with light or anything that could cast a shadow. He hid it from his family because they were already facing a difficult situation at home, but that was a mistake because one day she managed to take control, and this time he couldn't come back. The only way he could take back control was to hurt himself enough to recover his body, even for a few minutes, and as a last resort he took aim at his own eye.

The plan worked and he managed to regain control, but he was lost, alone, in pain and not knowing what to do, so in complete desperation he just ran, with no direction or purpose, just trying to get out of there. That's where he met someone, a creature that gave every signal for Remulo to leave, every one of his instincts telling him not to trust and run away, but it's not like he had many options and they were offering a proposal that could help him

He would be safe from his shadow and in return, all he would have to do was work for the creature, known as Shinki. All he has to do is guide the train and collect the souls that were lost wandering around the world aimlessly. Everything pointed to a prank or trap, but he was desperate and they were incredibly convincing, especially considering that time was ticking and his shadow could return at any moment so he signed the contract, without reading in the fine print that he would be linking his own soul to the train, making it impossible to get out

After getting stuck on the train it took him a long time to get used to everything, but he soon realized that he would have no sense of time on the train, so this was something he would have plenty of. Gradually his personality and way of acting changed (being alone and trapped in this place is not good for someone's mind) and he noticed that some of his memories were fading. He went on to keep a diary so he could be sure he wouldn't forget who he is or what he went through. It's one of the only things that keeps they sane. Zipora's coming from time to time also helps him, being one of the few constant interactions he has with someone who understands him, although he doesn't like her much for the fact that she works of her own free will for the creature that tricked him into this

His new personality and way of acting was also enough for the souls to invent all kinds of rumors about the conductor, most being the reason for the souls to avoid as much as possible come across with him. But even with the frightening rumours, the rare souls who meet him come across someone kind who will do anything to help them find a way out of this terrible place