Character archetypes in eroge (erotic games) are rigid. "Sister" can mean either a biological sibling or a "little sister" figure (Imouto). "Chika" is a common Japanese female name, but in VN circles, it is famously associated with heroines who appear sweet but harbor hidden depths (Yandere or manipulative traits). The "Sister Chika" in this context is likely a custom sprite or voice model—a generic doting sibling character repurposed for dark storylines.
The query "ntr sister chika v100 acerola hot" appears to be a specific set of tags or a search string related to independent adult-oriented gaming or digital art, likely associated with a creator or a specific update version ("v100"). Based on the components of the request: "Sister Chika" ntr sister chika v100 acerola hot