When I returned home, my sister had grown into a plump, delicious body and greeted me with a smile. But suddenly she snapped, "W-well, it's not like I'd be lonely without you, big brother." She activated her tsundere mode! While I was looking at my sister's panty shot, she fumed, "You pervert!" But my sister, who loves her big brother, secretly masturbates with his underwear! Seeing that, I...
