sin (guin guin)
The original "Doctor" of Guin Guin's Arknights universe. He is a Sankta whose wings and halo have been cursed with Oripathy since young. Together with Ratel, the two met the old man, who had been transported into Arknights' world, and became his adoptive children.
During the fateful reconnaissance operation in Chernobog, he makes his last stand along with Ace against Reunion holding them off to allow others to escape. He was confirmed to be killed in action by Team A4 in the aftermath of battle.