Why take turns when you can use another hole..?

Yeah, I mean really; the guy's preoccupied, and the girl's ok with it. Just wet the tip of your finger and poke right through that paper wall. :P

i wonder what the possibiliy will be that those 2 would smash right through that paper wall.

Instead of questioning about the peek hole, why not question why the hell their sister is okay with her two little bros watching her get banged?

Am I the only one questioning the logic?

Lordcross is right i am also wondering what is wrong with the logic here. Not to mention the morals of the older sister... something is definitely wrong here.

Isn't she more than likely the boys' babysitter? Onee-chan can refer to any woman older than them. Pretty much same as Ojii-chan here.
I'm assuming the man is the boys' father and they're having an affair or something.

It's abubu. Much of his work is straight shota incest.