姉巫女の淫欲なる儀式 ～我慢できないぼく～

In a remote rural area, far from the city, there is a shrine run by my grandfather.
Every year, my older sister visits there to help out my grandfather as a shrine maiden.
This summer vacation, I happened to be visiting my older sister and my grandfather's house.
When we got there, I found myself faced with a hectic schedule. I was constantly bombarded with chores, told to do this and that...
But no matter how cruelly my grandfather treats me, I have my older sister.
Plus...unlike back home, I get to spend more time with my sister, so no matter what, I'm happy.
But one day, everything changes.
It happened late at night.
My sister, who was supposed to be sleeping next to me, was gone.
While casually searching for her on my way to the bathroom,
I witnessed a shocking sight.
"Hmm, hmm...please...stop it..."