Crimson

One of the protagonists of this work. With androgynous features, they can change their gender and appearance at will. Their left eye has a vertical pupil resembling a dragon's. Their true identity is the former blood leader of the "Winged Bloodline" and a former dragon king who rebelled against the "Dragon God." They aim to exterminate all dragons, including themselves, and fought alongside Ragna in the future. The reason for this goal is unknown to Ragna from the future and remains unclear in the story. However, even from Ragna, who inherited the future version's memories, it is confirmed that they are earnestly trying to eradicate dragons, indicating trust in their intent.

In the present, they hide their true identity and infiltrate as a servant of Melgubede. When Ragna defeated Melgubede, who invaded Ronavela, they encountered Ragna. Ragna then proposed an alliance. Initially, they were interested in Ragna's silver combat skills but continued to refuse the offer while feigning ignorance. After recognizing Ragna's usefulness during the battle with Barom Shuera, they revealed their true identity and accepted the proposal. They have ambitions to use Ragna's abilities to create a unit equipped with silver weapons.

Although unable to use their dragon king powers, they can act without issue under sunlight. They possess various techniques, such as controlling the "aura" emitted by themselves despite being a dragon, adjusting Ragna's body's aura flow by stomping with their foot, summoning an armory from another dimension, and manipulating people's memories through suggestion. They achieve immortality by storing their heart in a separate dimension, allowing their body to reappear from nowhere in case of fatal damage.

They have extensive knowledge about dragons, not only their abilities but also their personalities. As they claim, from behavioral tendencies in battle to sleeping postures. This wealth of knowledge aids in strategizing against higher-ranking dragons.

Generally characterized by a calm and confident demeanor, they are a schemer who disregards human sacrifices for their goals. They attempted to force Ultimatia to rewind time and drain her magical power by bombing the capital, killing and injuring many citizens. During their alliance with the Silver Soldiers, they attacked Foo hoping to seize the teleportation magic circle and leave the country of Reza as soon as possible. Due to this ruthless nature, others view them harshly. Staria sees Crimson as a "dark mass of death" and calls them "filth," while Ragna agrees with Staria's metaphor of a "stubborn toilet stain stuck to the world." Even the author commented on the back cover of volume 4 that "anyone who sees that guy (Crimson) as a heroine should see an eye doctor."

However, they easily lose composure when situations exceed their expectations, such as when Majorca teleported them from the military training ground or when Ragna was unaffected by the poisoned cup. They also exhibit childish behavior, like sulking, when Ragna points out their lack of determination to eradicate dragons.