The person entrusted to take care of his parents on their trip—instead of his mother—is Niina, a woman radiating poised beauty and an overwhelmingly stunning figure that captivates everyone who sees her. Koji instantly falls for her composed demeanor and mature allure, but he senses in her eyes that she sees him as nothing more than a child, leaving him increasingly disheartened. Desperate, Koji commits a reckless act—stealing Niina’s underwear. When she discovers it, she merely smiles playfully, teasing, "Such a hopeless boy. Should I show you a special place?" and gently pulls him into her embrace. Drawn in by her warmth and undeniable adult charm, their relationship begins to deepen in ways neither expected.