My sister suddenly entered the bathroom wearing a swimsuit, saying she wanted to wash my back. She seemed to be trying to get a new summer swimsuit, but whether intentionally or by accident, she kept pressing against me while washing. Though I usually think of her as childish, her appearance in the swimsuit made me feel flustered. I tried to stay calm, but my body reacted involuntarily. My sister noticed and kept glancing over, eventually reaching out...
