The Mysterious Traveler In Terra (OC × Arknights)

Cos, an unknown man, from another world. He wasn't supposed to exist in Terra. He who has lived for eons mastering the power of time and space. What, has the world to offer for Cos in Terra? We shall see as the curtains unfolds. (Also, story would probably differ from the original. Which you probably knew, but just saying for those who dont know.) (Also, im not gonna include future chapters of the game. Only the main Reunion Arc)