The Plot I Got as a Cannon Fodder Was Completely Rewritten

[All-Rounder Heroine × Loyal-Dog Hero] One day, Chi Mu found herself inside a book. Wherever there was a pitfall, she had to fill it in. Chi Mu had only wanted to be a nobody who lazed around and waited to die, but the System had other plans: “The plot’s gone off the rails, and the supporting female character is dead. Go take her place.” So Chi Mu took on the role of the wicked supporting heroine, playing the expert green tea for a hundred years and tossing her scruples aside. After finally making a name for herself with the supporting character’s persona, the System brought her more bad news: “The plot’s gone off the rails, and the heroine is dead. Go take her place.” So Chi Mu gritted her teeth and picked up the heroine’s script. Ugh! Why does this ridiculous plot never stick to the script?