Solum

Solum was born in a slum outside Ranshin City. When he was still a child, Ranshin City underwent an expansion, providing the slum children a chance to live and study in the city, but he was always ostracized by others due to his humble background and for being poor at his studies. The numerous conflicts that eventually developed into physical clashes ultimately made him drop out of school, though thankfully, he didn't just give up on himself.
Not wanting his behavior to affect how others treat his sister, Solum chose to contribute to urban construction after leaving school and was quickly recognized for his naturally advantageous physique and brilliant performance. After work, he'd put in a lot of hard work to improve the neighborhood he resided in, which attracted the attention of people who subconsciously began relying on him. This became a perfect opportunity for him to gather these people to work on improving their living environment altogether.
When Solum left the construction company, he and his small team founded a private security team that maintained peace and stability at the borders. With their hard work, a prominent decrease in all sorts of conflicts was noted, but a bunch of people began seeing the security team as an adversary, for the team had caused them financial losses. One night, these resentful people attacked Solum. In his last moments, all that filled his mind was his worry for his sister, and without warning, his ascension abilities were awakened.
His unique ascension abilities transferred his consciousness and strength to his motorcycle helmet, allowing him to communicate with his sister through telepathy from then on. Even though he would be able to temporarily exert power through his sister's body if she put on the helmet, to avoid drawing their adversaries' attention to her, the siblings came to a decision to join the secretive Night Chains to make a living, and Night Chains also welcomed them with open arms.

Once in a while, when chatting with Solum, the 'sister' will recall the times when she lived with her brother. She would rush out of school after club activities ended, go to the supermarket at the corner of her home street to get discounted groceries, and then head home with shopping bags in her hands, yelling 'I'm home!' at the doorway. That tiny, worse-for-wear apartment might not be worth mentioning to others, but it was purchased with the money Solum earned with blood, sweat, and tears, a warm refuge for the siblings.
Usually, the brother would come home before sunset and make the only food he was good at making—curry rice. While he busied himself in the kitchen, the sister would tidy up the rest of the apartment or sort out the homework she brought home from school. By the time dusklight shone into the small room, the brother would be done making dinner. All the meat that was already placed on the sister's plate would be discreetly returned to his by her while he was distracted.
Sometimes, when the brother had work and couldn't come home, he never failed to give the sister a call, speaking at the top of his lungs, "I'll be home late tonight! Eat on your own, okay? Don't go hungry!"
That evening was the only time she sat waiting on the dining chair until night fell, and he still didn't come home.

Even though Solum can only live on the train as a helmet these days, he's still really happy. According to him, he has found solace among a bunch of weirdos. "I know Night Chains has no lack of weirdos either, but it's different on The Eternal! You get it, right?"
Right after he said that, a certain passing Night Chains member knocked the helmet cheekily. "Are you hinting that us Night Chains peeps aren't good enough?"
Of course, that wasn't Solum's intention, but he seemed to genuinely like the vibe on The Eternal. To express that he shared the same sentiment as his sister, he purposely returned control of the body to his sister temporarily, attempting to let the shy and quiet girl speak for herself. Needless to say, it wasn't really a successful evasion. She merely mumbled an "I think so too" before letting him take control again.
Outside of combat and work, Solum has found a new hobby—studying curry recipes from everywhere to try making different but absolutely delicious curry rice. His culinary skills have definitely improved, his testers receiving raving reviews from the other crew members.
Should you visit the dining carriage at dinnertime, you might just be able to bump into the Solum siblings making a new type of curry rice.