正しい姉妹の調教方

It all started from my father's statement: "I've decided to remarry!"
I could only sigh, honestly. I've got accustomed to being flung around by his whimsical acts, but still I'm half-astounded. Ignoring my astonished state, he asserted to enact his plan regardless.

"Rejoice, for you will have sisters, two of them!", so said my father. It was shocking. "Sister". My heart tightened at the mention of the word. To tell you the truth, I have a wish I can't tell others. That is leading a life of frolicking around and doing erotic thing with my sister everyday. Not an imaginary sister you can find in manga or games but a real one.