Otouto no Seiyoku Shori wa, Ane ga Suru Mono da to Onee-chan wa Omotte iru.

My father just remarried, and I now have a stepsister around the same age as me. What's more, is that I'm using her as my own personal fap-pet! She's the shortest at school. She's also got the biggest bust! For some reason, she's under the impression that it's her job to care for my sexual needs, an