Higashi Sandis Ryokaku Tetsudou: Basha Shikanai Isekai de Tetsudou Gaisha Hajimemasu

Sandis is a continent in a world of swords and magic. Mark, a young man living in a rural village, dotes on his younger sister, Milady, and devotes himself to his blacksmithing work, leading a peaceful life. One day, Mark spots a suspicious figure following Milady. To prevent him from harming his sister, he captures the man, but it turns out he is a train enthusiast who calls himself "Tetsu" (Iron)...!? (Source: Shogakukan, translated)