Based on the erotic doujin game by Tsukkii no Ochakai (つっきーのお茶会).

Alice is an ordinary girl who is a little timid and loves her big sister. When she finds herself separated from her sister in a strange room, Alice is in a lot of trouble. She is so lonely being in a strange place all by herself. "What should I do... onee-chan..." But Alice gathered up all her courage and tried her best to leave her room to look for her sister. But be careful. That room is very dangerous. It is full of strange and scary creatures and traps that can kill her. If she makes a mistake, she will never see her sister again. But if she doesn't have the courage to try, she won't be able to solve the mystery. Will Alice be able to find her sister safely? When she wakes up, there is a white rabbit... A white fluid was poured into her body.

(Source: Getchu, translated)