You are the ray of sunshine in my heart that can illuminate even the darkest corners of my heart. She is a prodigy in the world of weapons design and a target of key national talent training. However, her past heartbreak makes it difficult for her to believe in love. He is the legendary prince of Kyoto from a standard red family, and his trademark is ruthlessness. When she meets him, will she be able to see his deep-seated love? Will he be able to refine steel and turn it into tenderness for her?