After the Mission Failed, I Was Imprisoned by the Yandere Villain

I traveled into the novel and my mission was to prevent the villain from turning dark. The system says that as long as he feels love and warmth, he can be saved. For ten years, I stayed with him and became the only light in his dark world. I thought I succeeded because he seemed so normal and even gentle and considerate to me. Until the system announced that the mission had failed and was preparing to erase me. I closed my eyes and waited for death. When I opened them again, I saw his scarlet eyes. He crushed the system light ball and locked me into a golden cage. "Sister," he stroked my face and chuckled, "do you want to redeem me, or do you want to leave me?"