Transmigrate into a Book and Become an NPC

Qi Yanran's death this time around made no sense. Just as she managed to live again, she was bound by the idiotic System in the book and turned into a cannon-fodder tool character. She had it rough... But to complete her mission, she gritted her teeth and threw away all dignity, just to help the male lead win the heart of his beloved. She thought that once the mission was complete, she could leave with her work done. But who could have guessed that the male lead would inexplicably dump the heroine... W-was he planning to keep this tool character around forever? How long would it take her to finish her mission then??? Damn it, she wanted to blow up the System, but before she could, why had the male lead carried her home? What was going on? Answers wanted, please! How can a tool character escape being taken advantage of against her will?