A black angel who possesses equipment similar to that of Metatron and invariably appears to confront the white angel. He is a member of the Black Lodge's inner circle but stands apart from all of them and shows little interest in fighting weaklings. Sandalphon typically plays a minor role in the story but becomes the primary antagonist in Leica's route.
It is revealed that his real name is Ryuuga Crusade (リューガ・クルセイドRyūga Kuruseido?), Leica's brother and another test subject in the Moonchild Project. Although he was male and therefore did not have a real prospect of becoming the C Priestess, he was still experimented upon and had a magical dynamo implanted into his body, giving him superhuman combat ability. Although he did not know what the ultimate fate of the test subjects would be, Ryuuga still distrusted the scientists and planned to take Leica and escape. He loved the sky and his dream was to fly with the birds. Ryuuga's first escape attempt was successful but he was overpowered by Vespasianus, while his second attempt was cut short when Leica was manipulated into attacking him. He sustained severe injuries and was placed into a coma. Ryuuga's memory of the incident was distorted and he believes Leica killed him, causing the birth of a hatred that would eventually turn into an all-consuming obsession with killing Metatron. Vespasianus provided him with his equipment and gave him the name Sandalphon, making him an agent of the Black Lodge.
Sandalphon clashes with Metatron repeatedly over the course of the story and in Leica's route, he is drawn into the scene of the final battle along with Demonbane and Liber Legis. Without Master Therion, Etheldreda is incapable of fighting Demonbane on even terms and attempts to take control of Sandalphon to use as a pilot but he turns on her, consuming her and gaining the full knowledge of the Pnakotic Manuscripts. With it he takes control of Liber Legis and battles Demonbane. He is defeated but continues to battle Metatron on foot. Leica deals him a fatal blow and he dies in her arms, in a state of peace, if not sanity. In all other routes he is killed by Metatron in a duel near the end of the story.
Sandalphon is a master martial artist and the magical dynamo implanted into his body gives him superhuman strength. In addition his armour provides him with enhanced durability, flight, and a voice scrambler that hides his identity. His pathological hatred of Metatron grants him a measure of resistance to pain and allows him to endure otherwise crippling blows. When he consumes Etheldreda, Sandalphon becomes capable of piloting Liber Legis and using all of its arsenal.