30 Lewd Days with My Adolescent Little Sister

Circumstances beyond their control leave a brother and his sister sharing an apartment for thirty days straight, and she's hit that awkward, standoffish age where she barely wants to talk to him. So they talk anyway, poke at each other, and try the kind of small dumb pranks siblings try when they're bored and too close for comfort.

The month is the whole structure: living under one roof forces daily contact, and daily contact is where things start moving. She stays guarded at first, but the walls she puts up don't hold once the days pile on and the two of them end up alone together more often than either planned.

You spend your time managing that shared routine, choosing how to interact with her from one day to the next and pushing on the moments where her guard drops. It plays like a slow-burn cohabitation sim rather than a straight visual novel, with her trust and comfort shifting based on how you handle each encounter, private-room scenes included.