Boku ga Boku ni Koufun Suru Wake ga Nai! ~Onee-chan no Otouto Josou Kyouiku~

"She really is something, huh... Chisa-senpai..."
"I guess so..."

My classmates sigh as they stare through the window at my older sister, Chisa, eating her lunch in the courtyard. Bathed in warm sunlight, she’s wearing a radiant smile, completely unfazed by all the eyes on her. There was a time when I felt just a tiny bit proud to be her little brother...

"I’m home."
"Welcome back—"
"Augh..."
"Hmm~? What’s wrong? Getting all shy just because the sister everyone adores came to greet you?"

My sister grins at me as I freeze in surprise.

"So, what shall we do today..?"

All I can do is wait in silence for whatever she’s about to propose. The longer the pause, the more certain I am it’ll be something outrageous...

"That’s right, either way, first you’ll have to strip!"

There it was: the other face of my sister that only I know.

[Translated from the official site]