Niece 4 Darkness’s mistake

「……san」
「……Onii-san」
When I opened my eyes because of the repeated chant-like call, Nana-chan approached to the point-blank range that it looked like she was just before the tip of my nose.
「Uwaーー」
In the narrow room, everyone is sleeping together in a huddle at a suitable place. In such a place, on the right side of me who was sleeping on the loft is Akira-chan, who lets out cute sleeper’s breathing.  And on the left side……it goes without saying, Nana-chan takes up that place.
When I barely suppress my voice because it will be bad if everyone wakes up, Nana-chan whispers quietly with the sick eyes (みんなを起こしてはマズいと辛うじて声を抑えると、奈々ちゃんは病んだ瞳でそっとささやく。) 
「Onii-san, can I kiss you just like this?」
「E!? S, such a thing is no good. After all, Akira-chan is sleeping besides」
「Akira-chan won’t wake up so don’t worry. Besides, I already said about the punishment, right?」
When I smile slightly, Nana-chan takes out her smartphone and shows off the screen. ーーThis, this is!?
The picture of me sleeping peacefully with a pantsu on my head, the picture of me sleeping with my whole face smiling and my hand concealing the nearby Akira-chan’s neither region, the selfie picture of Nana-chan embracing me nakedly, etc……numerous things that can end my life instantly if they are seen by other people was shown.
「Ha, hahaha……Nana-chan, you have a smartphone?」
「Un, father bought it for me. And, taking this away is no good, you know? Because I already sent all photos to my mother」
W, what!? If nee-chan sees the such pictures, I can’t live anymore!!! I can somehow if it’s my other sisters, but if my gentlest, beloved Michika-neechan thinks of me as 「Loli pedo incest boy」…… (ロリペド近親相姦男) 
When I check my phone which is near my pillow in a hurry, a mail from Michika-neechan was mixed up with the spam mails.

「We need to talk. I will call tomorrow」

With these short sentences without any affection, I hang my head in despair.
「Onii-san, don’t worry, if you do as Nana says, I will explain to mother that it’s just a prank」
When she said so, my lips were taken forcibly.
「n!?ーーn」
As if memorizing it from somewhere, Nana-chan opens my mouth and invades using her small tongue. Her cheeks, nose, lips, and tongue……everything was unbelievably soft, I was violated by the sweet smell without any impurities……combined with the darkness, I involuntarily forgot myself. In fact, I couldn’t suppress my s.e.xual excitement, and my thing rose, too.
「Onii-san, we will marry for real with this, right? Because we also kissed as well, after this, we will also do ecchi thing, right?」
Nana-chan hides her hands in my underwear, and suddenly grasps my completed (?) thing gently. (the (?) is in the raw, which means his thing is already at its MAX) The cold, tiny hands gave my hot pole even more excitement, I who went through the fear of her threat unintentionally hugged Nana-chan *gyuu*
「Onii-san!?……I’m happy, you like Nana like thatーー」
But such words didn’t go to my ears. I put my own hand on Nana-chan’s hand, while rubbing it fervently, the target as my 「side dish」 is…… (side dish/okazu = slang for fap material) 
「Haa haa, A, Akira-chan!」
For some reason, I fully released my desire to the pure sleeping face of Akira-chan who was sleeping innocently nearby.
「S, Sorry!!!」
While hugging Nana-chan with one hand, I released my desire, Akira-chan’s neither region……was splendidly dyed with cloudiness.

「n……bed-wetting, not again……」

Together with Akira-chan’s sleep-talking, I could hear Nana-chan’s incantation of death.

「……this is, the material for baby, right……while hugging Nana tightly, you let it out at Akira-chan, what does this mean……I wonder? Tomorrow, I will try asking mother」 (赤ちゃんの素 cant find good words for this)