There's Touya Mochizuki, of course. Then there are the various female characters who play important roles in the story. For instance, Yumina Urnea Belfast, a princess who becomes an important part of Touya's life in the other world. There are also other characters like Leen, a magician, and Elze Silhoueska, a swordswoman, who all interact with Touya and contribute to the story.
The main character is Touya Mochizuki. He is a likable and intelligent protagonist. Besides him, there are many other significant characters. Yumina is a princess with a gentle nature. She is one of the first characters to befriend Touya in the new world. Elze is a strong and brave swordswoman, and Linze is her sister who is more into magic. These characters, along with Touya, drive the plot forward with their different personalities, skills, and relationships.