I splurge on a hot-spring trip because my girlfriend refuses sex unless the mood is perfect, only for her to bring her adult sister along and ruin my plans. But Nana, despite her innocent appearance, is secretly insatiable and begins tempting me as soon as we reach the inn. “It doesn't count as cheating if I only use my hand, right?” she whispers. Racked with guilt but unable to resist her devilish teasing, I let her stroke me again and again with her toned body pressed close, becoming the worst kind of boyfriend as she drains me repeatedly over our three-night stay.