I Transmigrated into the Hero’s Ex-Girlfriend and Have to Follow the Plot

[Transmigrate into a book + System + soft, sweet heroine + devoted to each other] Content warning: sugary sweet at first. [Completed] Zhang Xingxiao transmigrated into a campus novel as the male lead's shallow, money-loving ex-girlfriend. She was currently dating him. The System required her to complete the campus storyline, after which she could switch to a different body. Zhang Xingxiao happily agreed. She'd get to live another life, after all. So the System set the tasks in motion, and Zhang Xingxiao did her best to complete them. Meng Ruizhe watched his girlfriend grow cuter by the day, his heart melting. How could she be so pretty? She liked him so much. She was so clingy. Before he knew it, she had him grinning from ear to ear. [Host, there's only one day left until the breakup.] Zhang Xingxiao: [All right, System.]