Based on a romance visual novel by Tinkle Position, this story follows a young man who, as a child, grappled with severe asthma. To support his health, his four younger sisters took turns sleeping beside him each night. When their scientist parents propose an experimental method to boost his immunity through daily hugs, the siblings embrace this new routine eagerly. The protagonist, determined to show his deep affection, begins to hug his designated sister each night with unprecedented warmth and care, leading to unexpected bonds and heartfelt moments.