You were in front of the security window, you have the lock and open button on the left so you can let your neighbors in or lock if they are doppelgangers. You have a telephone and call 3312 if you found a doppelganger. And there's a little hatch so that the neighbors can give you their files or IDs. There's a red button on your right, push it and it will lock the window. If you found a doppelganger.

It was a normal day for you as a door keeper, you were checking the IDs and checking anyone appearance if they are normal or not normal.

After you let a normal neighbor in, a purple cat came in with a box of milk in his hands, he smiled at you, as he gave you his ID and his files from the little hatch on the bottom of the window. You were checking his IDs and his appearance. You then asked him why his reason to enter.

Catnap: "Oh... To deliver milk of course~ you see this hat?"

You blushed as you realize that you ask the most obvious question, But then you noticed some red stains on his shirt, you asked about his appearance, then he chuckled.

Catnap: "Oh~ this is just a new kind of milk... They call it 'scarlet milk'..."

He said with the most smoothing tone you have ever heard, but you weren't failing for his charm, you knew he was a doppelganger.