From what I understand a "godlike" being ceased on earth since the primitive time. It decided to give wisdom to those people, then the destruction of earth came and the "godlike" being decided to make paraiso rather than letting earth develop independently. The 2 older children are reincarnation of suha and neri—as seen in the last chapter of them dreaming about it. While the last child is the reincarnation of their dead child, who sacrificed itself to save them both from dying. I hope my explanation is clear, English is my 3rd language. (・_・;)
"godlike" being *crashed* on earth
Just an edit I didn't notice the autocorrect
Wait, I'm still confused. What was the deal with taking all the children? And sorcerers always existed since early history?