NAIAD-007 AI live-action version: Dangerous photos of father-in-law and sister

[The long-awaited AI live-action version! Keep the atmosphere the same! ]This is a story from last year when I went back to my parents' house during summer vacation from college. My family consists of four people: my mom, me, my younger sister, and my father-in-law who remarried a few years ago. When I returned home for the first time in a while, the thing that surprised me the most was my younger sister's growth. She had grown taller, her breasts had become bigger, and she had become more feminine than I had imagined, so I was quite frightened. After taking a bath