While shopping together, a close sibling pair excitedly discusses their long-awaited family bath at an onsen (hot spring). Despite trying to act tough, when they start washing each other, the younger brother becomes fully erect, revealing his virginity. The beautiful older sister also gets aroused despite having a boyfriend, causing them both to engage in passionate intercourse without hesitation. This leads to a steamy encounter filled with incestuous love, resulting in a special release that captures all the intimate moments between these two siblings.