My sister's bath was so long that I went to check on her, and she had collapsed naked from a fever! I rushed to look after her, but when I calmed down and looked at her, I could see her big breasts even through the towel, and I couldn't help but get an erection! I tried to leave in a hurry, but my sister noticed and tried to get up, and she staggered and grabbed... my erect penis! There was an awkward atmosphere for a moment, but my embarrassed sister gradually became excited as she looked at my erection. Unable to hold back, she greedily grabbed my erect penis and asked for it again and again, saying thank you!