At dusk, a boy sits on a park bench, staring into the distance. A listless older woman approaches and sits beside him. Without introduction, she begins speaking in a gentle voice: "You know what rakkyo is? They're baby onions." The statement is entirely false, but she delivers it with perfect seriousness. This is the beginning of a strange daily ritual. Every day, the older sister—whose name, age, and background remain unknown—appears to feed the boy a stream of utterly worthless lies. She claims absurd trivia, fabricates life stories, and invents nonsense with a deadpan demeanor. The boy listens, sometimes questioning, sometimes accepting, as their time together becomes a curious comfort. The manga follows their quiet encounters, gradually expanding from the park bench to other locations: a guided tour of a zoo filled with fabricated animal facts, a aimless walk through town where every landmark comes with a fake history, and eventually the introduction of a friend who joins the absurd conversations. Despite the lies, a genuine warmth grows between the two, and the routine of meaningless talk fills an emptiness in both their lives. The story is a slice-of-life comedy that finds meaning in meaninglessness, as the older sister's cascading nonsense becomes a soothing presence in the boy's ordinary world.