Actually, there's a lot of them.
The very first AISHIMAI is an old DOS bgame from Elf/Silky, also called LOVE SISTERS. There's a famous ero-anime based on it. Review for the renewed version
here.
Years after was made a bgame-sequel called AISHIMAI TSUBOMI. But with other characters. Also had an ero-anime based on it.
I'm not sure, but this one looks to be the 3rd installment for the "Aishimai" series. And again involving two sisters, but this time looks to be more a romance/comedy-themed bgame. All the others were dark-themed bgames involving blackmail, domination and humiliation.