Board Thread:General Discussion/@comment-29602226-20180531212622/@comment-29325824-20180601151727

As much as that makes sense, it is also stated repeatedly that one of any Mamono's biggest desires is to have her own children. It's part of why the DL is trying to overcome the current setting and why the tentacle forest and its central tree exist. Plus, numerous species (forgot which ones exactly) have been stated to developed or awakened the ability to procreate upon becoming Mamono because that's part of what they are.

I personally think that maybe Golems, Undead, Ghosts, etc. might still be able to reproduce. The only ones I'm not sure enough about are Automatons, Ittan-momen, and others that don't even have genuine reproductive organs.

Honestly, it's something I've been wondering myself as well and it's very confusing.