I think that using one of the Illusion games for character models is more an ease of use thing than a cultural one.
All (?) or a lot of the Illusion games come already with in-build tools for editing poses and other things like that
and I think that makes it simpler to create scenes for a VN than the use of DAZ3d.
Buut I don't know a single thing about DAZ3d so take it with a grain of salt.
The main things are:
- not everyone like HS. Nor work with, nor play
- Illusion games are exactly what they are - games, not 3D art making tools. Meaning, you use screen shots of preestablished poses or heavily mod them yourself. Completely opposite of Daz, which is a special soft for making 3D character art for VN, promotions, art, etc. Yes, you do change stuff like this, but results are different, just compare most daz and HS games
And also
Is the developer japanese? If so then I think it is kind of rare for them to modelling the character by using daz3d but not something like honey select.
before any sjw white knight jumps on this, i'm 85% sure it wasn't planned to sound racist
With that out of the way, i can answer it more openely
We live in era of globalization
So it's not a neccessety or obligation to use only your country's soft
You use the one you like and switch if you don't
There is a lot of developers from all around the world that uses different soft for this