Akujo Kyousei Keikaku

A wizard named Arvel is killed by his fiancée, Seraphina, who later becomes the emperor's mistress and a villain. He awakens as his 13-year-old self and encounters a young, innocent Seraphina. Determined to avoid his previous fate, he aims to guide her into becoming a proper lady and prevent his brother's death. His efforts are complicated by Seraphina's indifferent family, suitors competing for her affection, and intertwining schemes. Arvel seeks to change her future and prevent her from becoming a villain.