I totally agree! Reira is really childish, selfish and inconsiderate. Regardless of scandal, I still hate that she hurt Shin-Chan and plays what I think are "mind games" by telling him she shouldn't see him but yet still tries desperately to cling to him via email and phone! she's probably messing the poor kid's head up, and this kid has already dealt with too much in his life!
And don't get me started on how she slept with Takumi, and then acted like it was something she never wanted in the first place! She needs medication, she can't make up her mind! And poor, preggers Hachi, she doesn't deserve the pain, either!
In conclusion, Reira is a real slut, and a very pshycologically unstable woman!

this whole thing is cofusing!
little ren can't be nana + ren's cuz they haven't met up for months
hachi + takumi cuz hachi seemed a little hurt when he was mentioned
hachi + nobu cuz no way on earth a father would let his son live in england that far away from him knowing that it's his
so the only thing i can think of is that he is takumi + reira cuz he might have got some of the half different issue thing that's why he prefers staying there --> the reason why junko asked nana to get a divorce.. but that would make reira really psychotic for thinking herself mature over not hating her own son

yes i gave it plenty of thoughts lol! x)

for NOW, i feel 100% sure that ren isnt reira, IRREGARDLESS of the attachment. Hachi is a mere month away from giving birth, and Future hachi and satsuki said so themselves, Ren is "ONIICHAN". So It wouldnt matter if he was related to satsuki or not, twins or from someone else's vagina. but LEGALLY he's the OLDER brother. so he was the first to arrive on the scene (whether he's hachi's or not).. even before satsuki.

At first, it could have been Reira's. But the older brother(check the raws since its not stated in the english translation since we, english speakers dont go calling an older brother, OLDER brother, casually like in the japanese culture) calling part gave it away that made it seem impossible to Reira's EVEN THOUGH she gives birth prematurely or she is pregnant. if you guess reira is the mother, thn you can also suspect that actress that takumi slept with to be the mother, since he slept with her earlier than reira. but of course, i dont think ill add that to any theory.
So unless ai yazawa plans to take back the part where he was called an older brother by hachi and satsuki.. then maybe you can guess away that he is reiras. But remember, LEGALLY he is part of the ichinose household. Ren, Satsuki, Takumi and Hachi, Ichinose. Irregardless who the parents are of the kids. The attachment became too strong to just break. If satsuki is 6 years old, and as some of you speculated that she ain't hachi's, she has been taken care of by takumi and hachi since birth. She loves hachi very much and she even spends time with her grandparents(hachi's) for the new years. She could have belong to Nana O(as some ppl think), but what will happen with the bond between hachi, takumi and hers? Just give her away to her "real mom" just like that? As for ren though, i got no idea what happened between him and Hachi, but AI yazawa made it seem like he is reira's at first. but The facts(stopping from chap 84) have went against it, so unless we find someone who is close to giving birth even before hachi, then we can confirm that hachi aint the mother. as for now, shes the only one about to pop out a baby and very soon(im sure shes 7-8 months already. I saw that from someone who made a timeline of hachis pregnancy). and Whoever is Lil ren's dad.. would it matter in the end though? i mean look at him now with takumi..

anyway, even though the mangaka returns to writing nana again, i THINK it still goes a long way to finish (i mean satsuki was already 6 years old).. judging by having two kids on the scene. IF theyre NOT twins, then they have a year apart from each other.. so lets say after hachi gives birth to whichever now.. then the next one arrives(doesnt matter who's birthmother), its kinda like 1-2 years apart. with those years, there are still an AWFUL lot of possibilities even though as of chap 84, things are falling apart already.