Looking for name of double incest manga

As per title, brother and sister do the deed but at the end they learn their parents are also siblings. This was on fakku long ago.

Fuck I read this too! I'll try looking for it and update you if i find anything.

Not sure if this is what you guys are looking for. But it matches the description. "Kyoudai ni Natta Hi or The Day She Became My Sister" by bobobo