You Can Have My Back, Vol. 1 (light novel)

When Ionia, proud knight of the realm, loses his life in a violent insurrection, his memories are inherited by a boy born one day after his death. Years later, Leorino Cassieux, fourth son of the Margrave of Brungwurt and blessed with angelic beauty, begins to see Ionia's memories in his dreams. He relives Ionia's ill-fated romance with the king's younger brother, Prince Gravis, as well as his death at the hands of a traitor to the kingdom! But as Leorino tries to make sense of the feeling swelling in his chest, he stumbles too close to the truth of that fateful day. The traitor's identity is revealed, and in a panic, the traitor threatens to end himself and take Leorino with him! As Leorino's life hangs in the balance, he instinctively cries out for his only hope: the love of his past life, Gravis.