Manabu moves in with his aunt, Junko, to attend a cram school in Tokyo. One day, his mother, Yurika, comes to visit and decides to stay at Junko's house with him. Feeling anxious about being away from home for the first time, Manabu becomes unusually affectionate toward Yurika. Though Yurika accepts her son's closeness, the situation unfolds in a relative's house—an unfamiliar environment. Manabu's uncle and cousin begin to watch the pair uneasily, disturbed by the blurred boundaries between mother and son. This tension, seeping through the cracks of their surroundings, threatens to transform their relationship into something far more dangerous.