In her previous life, she died saving him and swore that in their next life, he would be a man who protected her for the rest of her life. In this life, their souls switched genders as they were reborn, but the twists of time caused each of them to forget their past-life memories. Only the longing etched into their souls drew them together again, until they met, recognized each other, and fell in love, fulfilling a promise of protection that crossed the boundaries of life, death, and gender.
