When I was young my parents got divorced.
I wasn't sad, though, because I still had two older sisters.
Mayuri was from a previous marriage.
The other was my true sister Saki.
One was kind, one was kind of a jerk.
At some point I fell in love with them both.

But, reality isn't a game.
I couldn't let them know I had these feelings. I masturbated every day.
Eventually, though, something weirder happened.
Mayuri married my dad.

If that's what makes her happy...
And then I saw something on her cell phone that changed everything.

[From DLsite English]