After the death of her older sister, Yeorum 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, Yeorum chooses the path of a magical girl and resolves to find out the truth behind her sister's suicide. Original Webtoon: Naver Webtoon, Naver Series Official Translations: English, S.Chinese, T.Chinese, Thai