You Can Have My Back, Vol. 1 (light novel) by Minami Kotsuna
Leorino, fourth son of a margrave and blessed with the face of an angel, is the reincarnation of Ionia, a knight of the kingdom who died in the line of duty. At night, he dreams of his past life-his ill-fated love for Prince Gravis, and his death at the hands of an enemy agent. When he confronts the traitor as Leorino, he ends up arrested instead! His life in danger, he shouts the name of an old friend and his only hope...