Tokidamari no Hime Mangaときだまりの姫, , 刻だまりの姫, , 午夜公主, , Kokudamari no Hime , Princess of Time , Toki Damari no Hime
Story about a mirror princess/demon. It seems that a new condo building was built on a certain location where this princess was housed and worshiped with a stone monument but it was moved due to the new construction.
One room in particular seems to have a direct link to the princess who calls herself the owner of the pool of time. Beware when mirrors are placed opposite of each other because you may just be drawn in her world and powers.