Hmm. I haven't really played Now and Then (yet), but looking at the teaser images, I don't see the resemblance to any of the Ecchi Sensei characters. I would say it is no different then how lots of Daz games use the same models with minor edits. Look at my avatar. She shows up in dozens of games with slight modifications.
I can't speak for ils productions, but I think it is just a coincidence if you see the models as similar. As RandoCard3 said, Illusion generated characters tend to have a similar look, with less variety than you see in Daz games.