Shota invited his older brother's girlfriend, a woman named Yuki, to stay overnight at his house. Yuki had large breasts and a charming, big sister-like aura that instantly captivated Shota. That night, as she stayed over, Shota's curiosity about her voluptuous body began to grow. His mischievous desires intensified each day, gradually heating up as he spent more time with Yuki.