The day our parents both left for a trip, my younger childhood friend came to stay over at my place, leaving us alone to babysit the house. She's always treated me like a little sister—innocent and carefree by nature. Suddenly, she declared, "I want to take a bath together again, just like when we were kids!" and forcefully dragged me to the bathroom. I couldn't take my eyes off her as she casually started undressing. Every glance sent waves of arousal through me, making me fully erect. I desperately tried to hide my excitement, but when she walked around after the bath wrapped only in a towel, moving about freely, I finally reached my limit.