After losing her family, Erine, the knight commander who lived by the sword, died at the age of 30 from a mysterious illness. However, she suddenly finds herself back at 18—before joining the knights—and gets a second chance at life! This time, she decides to live as an ordinary count’s daughter and cherish her family. But no matter how hard she tries, she can’t help showing her knightly nature—swiftly helping others and standing up for what’s right. Watching her, a genius magician named Flyne takes an interest in her, calling it his “Erine Observation,” and begins to follow her around— I know who you really are. You were the extraordinarily strong Knight Commander, weren’t you? Can the strongest knight find happiness as a noble lady this time?