As the moon casts a soft glow through the window, a brother and sister find themselves unable to resist their growing attraction. The sister, a devout follower of the Koihime religion, struggles with her guilt as she feels her brother's gaze upon her. Their bodies aching with unspoken desire, they finally succumb, their hands tentatively exploring each other's forbidden territory. The brother's touch sends shivers down her spine, while she tentatively strokes his length, their panting breaths filling the room as they inch closer to the point of no return.