Island where woman are super fertile and extra curvy since all the men in the island left the woman here needs to be impregnated by someone so they could be saved from extinction and they need men from the outside of the island
Main leads:
Shuu: she's tan long black hair little top and black shorts she's very playful and h*rny sometimes

Hirika: shuu's sister black shorts short hair little top
And they invite you in their home she doesn't like s#x but she secretly does but won't admit