Crimson's true appearance isn't clear as he uses different identities to hide himself, the only consistent characteristic being the 2 eyes, the right one is green while the left one is red and dragon like but usually it's hidden by his long hair or something else. The identity Crimson choose to use the most while assisting Ragna is Crish Weiss, a magician or thaumaturge. He wears a dark brown magician hat with a golden symbol on it and a dark brown dress, adorned with golden lines, that leave his upper shoulders naked. His hair is crimson color, usually the same color in most identities he uses. On his neck there's a tattoo patter with unknown meaning. Crimson's skin is particularly light. Crimson claims to trust no one, even when collaborating closely with others. He's always one step ahead and he shows it by planning ahead and tricking anyone, whenever needed, successfully. Crimson doesn't lack knowledge either and in case he does he always tries first to get information by himself or through his servants before acting. Crimson's compassion only extends as far as himself; he cares not for neither dragon nor human. His ends justify the means, committing any cruelty or atrocity to accomplish his goals. Crimson's preferred method of action is through psychological warfare. In the rarest cases where his planning fails completely, he ends up in a tantrum unable to either understand where he failed or accept it. Crimson talks on a condescending, authoritative manner and looks down on everyone. He doesn't mince his words and is brutally blunt when expressing himself, often times psychologically and emotionally torturing whoever is on the receiving end of his cruel, but still accurate words. His utter lack of tact makes him come across as a "jerk" in Ragna's view, something Crimson doesn't even try to deny and in fact takes immense pride on it. Crimson is very secretive and manipulative, often times withholding information or being misleading.

He has striking white hair and typically wears a dark, sleeveless compression top that gives him a sharp, combat-ready look. He is frequently called "Ragna the Reaper" due to his grim aesthetic and the brutal weapons he uses. Ragna initially suffers from a deep lack of self-worth and survivor's guilt, which makes him reclusive and afraid to rely on others. However, his defining trait is his relentless, almost ruthless determination to eradicate all dragons. He is heavily driven by the need to protect the people he cares about and completely merciless toward his dragon enemies.