[K-drama Treasure Hunt] Falling book rescue moments

Welcome to the K-drama treasure hunt, where we all go looking for K-drama treasure in the form of tiny drama details that we know and love. Sometimes these details take the shape of well-worn tropes (oppa Band-Aiding) or storytelling devices (Top Secret Deadly Allergy), but other times it's just details we know we've seen in other dramas, but need help...