My younger sister, "Seira," can be charming and cute sometimes, but usually she's a mischievous little sister who teases me. However, perhaps because of the age gap, I've never been truly angry with her. Objectively speaking, she's very pretty, a petite beauty with sharp features. That was until that moment…

One night, in the middle of the night. I was awakened from my sleep by a rustling sound, a feeling of suffocation, and a strange, damp warmth covering my face.

I opened my eyes, still half-asleep…

"Eh… Ah… Huff… Ngh… Aaaah…!?"

Seira was actually pressing her private parts against my face.

"Oh, you're awake? Fufun… You can't escape… ♪"

I was confused, and tried to run away… But Seira, ever the prepared one, had restrained me to the bed.