Coraline's father's office is located in the end of the first floor corridor. Go along the corridor and when you are in front of the mirror, turn right (if you turn left, you will see the kitchen). In the office there are many boxes, a desk and a computer (in the real world, but in the other there is a piano and other musical instruments. This office is where the back door is located. Coraline's father is usually in there, typing articles for work. This results with him not being able to spend much time with Coraline.