After the death of her older sister, Yeo-Reum Han enters her final year of high school. But when a nap in class runs long, she wakes up to find her biology teacher and best friend in cosplay... fighting monsters?! Faced with death, Yeo-Reum chooses the path of a magical girl, and resolves to find out the truth behind her sister's suicide. With SATs approaching closer and closer, can she protect the love and peace in this world? 
 (Source: WEBTOONS) 
 
Note: Chapter count includes prologue and epilogue.