Dwelling in the Misty Valley, Rosine terrorized a nearby village, sending an army of insect demons disguised as elves to eat the town's livestock and people, as well as capturing children that she would transform into more insect demons via cocoons. Guts, Puck, and Rosine's former friend Jill travelled to the Misty Valley to confront Rosine, who offered to make Jill an elf apostle. Jill was tempted by the promise of flight, but was uneasy with the warlike ways of the elf demons who would kill each other for fun. Guts found and destroyed the elf demon cocoons, and an enraged Rosine battled Guts until she was so badly injured that she could no longer fight. As Guts was about to deliver a killing blow, Jill shielded Rosine with her body. It did nothing to stop Guts, but
before he could act, Jill's father arrived and shot him with an arrow. Guts was then attacked by the Holy Iron Chain Knights, led by Farnese. Mortally wounded, Rosine finally understood the moral of Peekaf's fable and in her delirium attempted to return home to her parents but ultimately succumbed to her injuries and fell from the sky to her death. In some translations, she is referred to as Roshinu.