What engine or program do you use to create the characters?Please tell me, I also want to do something similar
most likely Ren'Py
Well yes, but that is the engine for making novel games, Im referring to the one they used to create the characters.
I believe its DAZ 3D check out f95zone . to (remove the space) and ask there for some advice you can also find more games like this on that site
We use Daz3D and Blender. :)