A high school student living in a dormitory becomes interested in a woman's sexy symbol, the buttocks, due to his abstinence lifestyle. The older sister is very sensitive about her buttocks. However, she has a slight complex about the size of her buttocks. She thoroughly attacks her younger brother who is pleased with her buttocks. The younger brother becomes captivated by his older sister's big buttocks as she begs him to "stroke it all over and thrust it in from behind"... He can't take his eyes off his sister's ripe, plump buttocks that are unconsciously appealing to him. The big buttocks that gently wrap around him are the best!