I was making magic tools for my sister to be chosen by a magic-loving prince. At our family's exploitative magic tool shop, I was overwhelmed with endless chores, and I've reached my limit! I collapsed and was picked up by the 'Ice Duke'. "If you keep doing this recklessly, you'll die someday." "The quickest way for you to escape from your family is to get engaged to me." Under the Duke's somewhat S-like orders, I enter a fake engagement. Despite his intimidating appearance, the Duke treats me as a 'legendary magic tool maker', so I've completely recovered my energy, and I want to stay at the Duke's house forever. Meanwhile, my sister, flustered by my disappearance, steals and reveals the dangerous technology I was secretly developing. Because of my sister's blunder, my family's reputation is ruined. I take over the shop after my parents ran away, leaving behind their debts! My shop's customers include the prince who was my sister's former fiancé, a princess, and a knight commander's daughter? My magic tools have become quite famous throughout the country. [Book publication project in progress]