On his way to his friend Koji's house, Kenji overheard a conversation: "My older sister is scary, so don't make a ruckus at home, okay?" He couldn't imagine what Koji's sister was really like. When Kenji arrived at Koji's house that day, he met Koji's older sister, Chiori, for the first time. Her mature aura, subtly kind yet seductive smile, and the sensual silhouette revealed by her loungewear made Kenji's heart race. Chiori gently invited him, saying, "Feel free to come over anytime," leaving Kenji both flustered and excited by her words.