Edgar Crosstruger is a young swordsman who comes from the same world as the elf known as the Ice Princess, a parallel fantasy realm filled with magic and monsters. He is introduced as a member of a classic adventuring party, serving as its frontline fighter alongside his childhood friends, the holy mage Alicia Edelcia and the warrior Raiga Striga. The trio grew up together, and their shared history forms the basis of their trust and camaraderie as they explore dungeons and take on quests.

In terms of personality, Edgar is characterized by a desire to project an image of coolness and composure. He aspires to be a stoic and effective hero, yet this facade is constantly undermined by the presence of an older, bizarrely powerful figure known to him as Uncle. In almost every significant situation, Uncle inadvertently steals the spotlight, performing feats of magic and strength that far eclipse Edgar’s own contributions. This leaves the earnest swordsman in a position where his attempts to look impressive are regularly upstaged, a source of recurring frustration for him.

Edgar’s primary motivation is tied to his role as an adventurer. He is driven to prove his competence and courage, both to himself and to his peers. A key event that shapes his public identity is a battle where his party successfully repelled a large horde of goblins. This victory earned him recognition as a hero. His legend grew even further due to a misunderstanding concerning Uncle. At one point, Uncle destroyed a mountain with a single, overwhelming attack. The local populace, unable to comprehend such magic, misattributed the feat to Edgar’s swordsmanship. Consequently, he was given the grandiose nickname Mountain Slayer, a title he did not truly earn but must now live with. This illustrates his role in the story's comedy, as he receives accolades for events he had little to do with, while Uncle, the true architect of these miracles, remains completely unknown and uncelebrated.

Edgar shares a close bond with his fellow party members. He and Raiga view Alicia as a dear friend, having known her since childhood, though they explicitly state they have no romantic interest in her. His relationship with Alicia is one of mutual support and trust in the field of battle. The most notable dynamic within the party, however, is with Uncle. When the powerful but socially awkward uncle joins them for certain adventures, Edgar is forced into the role of a largely ineffective straight man. His respectable swordsmanship and tactical thinking are rendered almost irrelevant compared to Uncle’s reality-warping magical abilities, which can solve problems with no apparent effort.

Development for Edgar is closely tied to the discrepancy between his perceived and actual abilities. While he is a capable and brave young man, the story consistently positions him as an ordinary person in the shadow of an extraordinary one. He does not gain immense new powers; rather, he develops through situations that test his pride and his understanding of what being a hero truly means. He is forced to accept that while he may be awarded the credit for heroic deeds, the credit is often unearned, relying instead on the intervention of the uncle from another world.

Regarding his notable abilities, Edgar is a skilled and dedicated swordsman who relies on his combat training and instincts to survive. He is shown to be effective in battle, competent enough to survive dangerous encounters in a fantasy world. A unique and somewhat quirky habit of his is the tendency to give names to swords he becomes fond of, revealing a sentimental side beneath his cool exterior. This practice of naming his blades is his personal ritual, one that stands in stark contrast to the nameless, overwhelming power wielded by Uncle.