My sister used to be completely absorbed in her club activities, with morning and after-school practices every day. But now, my serious sister has retired. While she used to relieve her stress through sports, she's become a shut-in since retiring. When I peeked into her room, she was masturbating intensely and cumming over and over! Her excess physical energy has nowhere to go and has turned into an uncontrollable sexual drive? When I was caught peeking at her, I hurriedly apologized, but she acted strange... In fact, she directed all that lust, which masturbation alone couldn't satisfy, toward me! I'm drenched in sweat as my sister, overflowing with stamina and desire, pushes me to climax again and again! She's completely wearing out my cock, even though I'm bad at sports and have below-average stamina... Please, give me a break!