Namaiki na Imouto no Ana wa Ore no Mono

Little sister Erika.
Earnest personality, a good student with a clear mind.
Never had an interest in boys even though she's at that age... or so I thought!
One day I witnessed a side of Erika I've never seen before.
It was also my key to exploiting her for other things.
Erika's hot little body is mine for the taking, and the day has come to take it.

[From DLsite English]