Shun Canaan Praeses is a teenage boy originating from Agartha, an underground realm. Orphaned alongside his younger twin brother Shin after their parents' death, villagers rescued and raised the brothers, training them in combat against monsters and threats. During this time, Shun contracted an incurable, slowly progressing terminal illness. He possesses shoulder-length brown hair and green eyes, typically dressed in a long white shirt and black pants. Shun exhibits kindness, care, and protectiveness, especially toward Asuna Watase. He saves her from a monstrous creature, demonstrating bravery and confidence. Throughout their initial interactions, he maintains a positive demeanor, smiling at Asuna despite knowing his death approaches. Shun leaps to defend Asuna from the creature, sustaining injuries. He then carries her to a cliff to evade police. Tears stream down his face, signaling his awareness of imminent death, and they part ways at nightfall. The next day, Asuna tends his wounds and they listen to her radio together. Shun reveals his Agarthan origin and his journey to the surface world seeking an unspecified something. He bestows a blessing upon Asuna with a kiss on her forehead. After Asuna departs, promising to return, Shun gazes at the stars and lets himself fall from the ledge to his death. Shun's death deeply impacts Asuna, who initially refuses to accept it. His existence and demise catalyze her journey into Agartha with their teacher Ryuji Morisaki, who seeks resurrection for his wife. Shun's legacy persists through his brother Shin, whom Asuna later encounters. His clavis crystal, a blue key-shaped artifact, becomes central to accessing Agartha and attempting resurrection at the Gate of Life and Death. The final song Asuna hears on her radio before Shun's death is revealed as a memory transmission from a dying Quetzalcoatl, Agartha's guardian beings.