itch.io

okay i will give a hint, 

There will be a portal that can only be seen using a certain lamp.. 

going inside this said portal will lead to a shadowy figure following you to your world..

There a portal at the end of 2nd floor on the left side, when enter it you will send to another call "universe day break", u can encounter SCM-835-NP just by explore until u see a shadow dash through the windows , u can found 2 other girl  and rescure them (u must save they before u encounter with SCM-835 or else she kill both of them or just don't explore too far)