A voice from upstairs

This is a story from my childhood.

When I was a child I lived in a rented two-floor house.
Both my parents worked so I was often alone when I came home from school.
One early evening when I came home the house was still dark.
I called out, “Mum?” and heard a voice say “Yeeeeees?” from upstairs.
I called her again, and again got the same “Yeeeeees?” reply.

I felt she was calling me and climbed up the stairs.
When I reached the first floor I called her once more and the voice “Yeeeeees?” came from the furthest room.
I felt both uneasy and a strong urge to see my mother and started to walk towards the room.

But just that moment I heard the front door downstairs open and my mother come in, carrying a lot of shopping bags.
‘Shunsuke (my name), are you home?” My mother called in a cheery voice.
Hearing her voice made me feel instantly better and I turned back to go downstairs at once – but not before I had a quick glance towards the room.

While I watched from the top of the stairs, the door to the room slowly opened a crack.
For a brief moment I saw something strange in there.
It was an unnaturally pale face staring at me.