Ken to Tiara to High Heels: Koushaku Reijou ni wa Eiyuu no Tamashii ga Yadoru @comic  

Sword, Tiara and High Heels, Tiara and High Heels: The Duke's Daughter Has the Soul of a Hero, 剣とティアラとハイヒール～公爵令嬢には英雄の魂が宿る～@COMIC, Sword, Tiara and High Heels, 剣とティアラとハイヒール: 公爵令嬢には英雄の魂が宿る - ＠COMIC, Меч, Тиара и Высокие каблуки

In this story, Ortus, who was once the kingdom's hero, passes away in battle despite his promise to safeguard it for life. Upon waking up, he discovers that he has been reborn as Seretina, the duke's daughter, who is determined to become a knight despite facing numerous obstacles such as learning manners from her unpleasant mother, marrying someone she doesn't desire, and more. On her way to the royal castle, she encounters a demon attack that unveils her hidden strength that no one knew about. Seretina becomes a new heroine with the power to slay demons with one blow and captivate even high-society individuals with her beauty. Despite her exterior appearance, she is fearless on the inside, marking the beginning of her chivalric and heroic fantasy journey.