>>103932774
Biboo's a rock. Roboco/Cece's a robot so by default they'd have terrible holes unless they put some kind of mechanism in there like a fleshlight.
>>103932917
>the orange one regenerates her hymen every time she reincarnates
This is a good point. Definitely a fetish, though. I wonder if she's used to it breaking by now.
Cece if she DOES have a fleshlight installed might have a lube dispensor, though.
Nerissa/Shuba/Reine has a cloaca so it definitely can't be her.
Pekora's a rabbit so hers is definitely loose.
Watame's a sheep so if she's ever taken a trip to New Zealand or Wales, she's a no go too.

Believe it or not, I think it might actually be choco/towa/mel(rip). As succubi/demons, they definitely have more control over the muscles down there and can likely tighten up down there hard enough to crush a man if they felt like it.

Natural tightest would likely be Kanata due to the whole angel purity thing.

Loosest would absolutely be Kobo. Girl's basically a slip and slide.