Two brothers; one carrying the memories of a past life and one with memories of the future, do everything in their power to prevent the tradgedies of the future. 

Paxton Byron is the first heir to Lord Byron, who rules a small fiefdom in the east of the country of Lorain. What nobody knows is that he still holds his memories from another world. Peter 'Umbra' Norman was a legendary assassin responsible for the 'Red December' incident in which the major political figures in 78 countries were killed, including presidents, prime ministers, and parlaiment members. He promised to live properly if he ever got a chance, and he plans to keep that promise as he's reborn into a child. 

Goddard Byron is the second heir to Lord Byron and brother to Paxton, who has already lived a full life. When a demon invasion drives humanity to near-extinction; Goddard leads a team to kill the four generals leading the invasion. Costing the life of his entire squad, including his brother, Goddard just barely manages to deliver the killing blow as he is impaled himself. Dying in the center of enemy territory, Goddard could only smile that he had saved the world, and only wished that he could do it again, but better. When he opens his eyes, Goddard is a child in his family home. 

While the two brothers work to save the world from the future invasion, they unwravel a world far beyond their previous understandings and try not to get chewed up in the machinations of a secret that threatens all they hold dear.