My Sister the Living Onahole: Sayaka Is Onii-chan’s Personal Sex Toy.
One day, our protagonist returns home to find a strange hole in the wall separating his room from his younger sister’s. He peeks through and sees Sayaka masturbating. The next day, he musters his courage, faces the hole in the wall, and sticks his penis through. Sayaka pretends it’s a mushroom and starts to lick it. Sayaka, who struggles to show her honest feelings to her brother, has her deepest desires fulfilled thanks to the hole in the wall. They have sex, she gets creampied…