The day I was left alone at home with my older cousin. As a reward for finishing my homework, the kind and cheerful older sister Rinka offered to teach me something naughty. We took a bath together, and while she washed my body, she playfully teased me until my penis swelled up...! She promised to show me how to make it better, but since I still can't produce semen, my arousal just keeps building. At night, she cuddled beside me and gave me a heart-pounding first sex lesson, taking my virginity and thoroughly draining me.