Building Harem And Dungeon With Monster Girls

One day I was suddenly thrown into a fantasy world with my sister,bff,fav. actress,milf next door, fav. pornstar,etc...

There I also met several mystical women from different species like mermaid,elf, Demonic, warrior, village girl,etc...

But who was the mysterious motherly woman who brought me here?What was her motives?

All I remember is that few days ago I....