HUNTB-335 "I want to learn how to swim!" While doing 'so-ko' with my sister in her swimsuit... I ended up teaching my sister, who hates swimming class, how to swim. Unable to resist the swelling of her developing chest, I got an erection...

I ended up teaching my sister, who hates swimming class, how to swim. I couldn't help but get an erection from her developing breasts and couldn't teach her properly! Then, noticing my erect state, my sister asked, 'Hurry up and teach me properly, what do I do about that (erect dick) to make it go down?' I couldn't hold back and wanted her to let me have sex with her, but she hesitated, saying, 'That's still too much...' I thought our sibling relationship was over and was desperate, but seeing how disappointed I was, my sister suggested, 'Well, if it's just rubbing...'.