In the Taishou era, Saeki Touka is suddenly cast aside when her engagement is unilaterally annulled. Soon after, she is murdered—and her life meets to a tragic end. But when she opens her eyes, she finds herself back at the age of seven. Clinging to the clues from her final moments, she resolves to unmask the culprit and change her fate. In this second life, she swears to seize happiness.