Unlike many of his peers at Regarden Magical Academy, Rosti never looked down on Will Serfort for his inability to use magic, even before Will’s victory over Julius during the Great Magic Festival. He has immense admiration and deep feelings for Will, which at times border on obsessive, causing Colette to view him as dangerous.

His attachment to Will is so intense that Colette actively prevents him from getting too close, especially during moments when she feels threatened by his presence. A notable instance of this occurred when the three of them went shopping together, with Colette deliberately blocking his attempts to get closer to Will.

Rosti Nauman has a slightly androgynous appearance, with medium-length blonde hair and blue eyes. His typical attire consists of a light-colored shirt with two pockets, dark-colored pants, a belt, and a bolo tie, reflecting the standard style of Regarden Magical Academy students. His appearance gives him a refined yet approachable demeanor, complementing his unique personality.

Rosti came from a family with a scholarly background, which influenced his preference for magical research over combat training. At Regarden Magical Academy, he excelled in magical studies and theoretical applications, often impressing instructors with his deep understanding of arcane principles and spellcraft.

Upon meeting Will Serfort, Rosti was initially intrigued by his lack of magic yet unwavering determination. Over time, their roommate dynamic evolved into a friendship, with Rosti frequently offering insightful advice, study materials, and strategies to help Will navigate the academy. Though he never directly intervened in Will’s battles, his presence provided emotional and intellectual support.

Rosti Nauman is a highly skilled Magic Artificer (魔工師), specializing in the creation of magical items. Despite lacking innate talent for magic item crafting, he is considered a genius in the field and has successfully developed various magical tools and equipment specifically designed to aid Will Serfort, compensating for Will’s lack of magic. His ingenuity and craftsmanship make him an invaluable ally, providing customized gear to support Will’s unique fighting style.

In addition to his talent as an artificer, Rosti is also capable of using Water Magic (水魔法), though he primarily focuses on item creation rather than direct combat. One of the spells he has demonstrated is Crysto Wreath, a low-level water spell that fires a stream of water at a target.

To enhance his magic and artificing abilities, Rosti wields the Gear Wand (歯車のワンド), a specialized wand that likely assists in both spellcasting and the crafting of magical tools.