My Mischievous & Mysterious Junior Sister

My Mischievous & Mysterious Junior Sister Plot:

Lin Chuan, a junior in medical school, is driven to the edge by his junior sister Su Xiaotang—the cute double-ponytailed girl who replaced his lab frog with a pink toy (getting him scolded by the professor), crashed his blind date by yelling “Brother, have you forgotten our promise?” (scaring the girl away), and even texted a “prophecy” that he’d be scratched by a cat (which came true). But when he confronts her with the toy frog, he catches her labeling anti-allergy medicine—she knew he was allergic to frog hair; the blind date was a gold digger, so she intervened; the “prophetic” stray cat? She fed its mother to distract the dog that was about to bite him… Is this mischievous and mysterious junior sister a little devil tormenting him, or a guardian hiding in pranks?