I read this manga a long time ago and I'd like to reread it.
It was a supernatural manga. The first chapter focused on this young couple. They moved into this apartment together but for some reason the guy goes missing and the girl can't find him. Sometimes she'll be in the house and then all of a sudden there is blood everywhere that belonged to the guy.It turns out the guy was trapped in this mirror that came with the apartment because a female ghost/god who looks like a child thought he was interesting. Eventually his girlfriend figured out that if you use a pocket mirror to reflect into the larger mirror she could access the other world and save her husband.
After the first chapter, the couple moves out and the protagonist for the rest of the series is the guy's younger sister. She ends up moving into the apartment as well and befriending the girl in the mirror. She then utilizes the god's power to gain the affections of her sempai who seems to be shunning her on purpose. It is later on exposed that her sempai has a similar god as well and has been using the time stopping powers to commit murders.
The series kind of ends abruptly there. If anyone knows what this manga is please tell me the name. I would like to reread it and see if it was truly finished.