I need your help, please

the story starts when the protagonist gets a package from an unknown sender. he opened the package and found a CD. he decided to play the game but when he inserted the cd, suddenly a light emited from the screen and sucked him in.

and then, he find himself in an another world. after walking for a bit he found a house. the moment he got near the house, a text appeared. it says 'this an empty house. do you want to own it'. the man choose yes and he got inside the house. but unexpectly, he saw four girls there.

after some introductions and turns, the girls joined his harem. but afterwards, the harem started tortured their master and treated him like a slave.