The Storeroom

Note: I'm not the author of this story. I've translated it from the original Japanese into English. Please do NOT copy and paste it somewhere else on the web without my permission.Thank you for your cooperation.

The end of one corridor in my house was a cul-de-sac, and my father, who had just retired from his job and had too much time on his hands, said, "We can make use of that space by turning it into a storeroom," and set out to make one by himself.

Like a man possessed he kept at it, and within less than a day managed to construct a storeroom with a shelf and a door.
The day after that I came home, but my father, who should have been at home, was nowhere to be found.
I wondered if he was still working on the storeroom. I went to the corridor but he wasn't there. I only saw a padlock hanging on the door of the storeroom.
In the end my father didn't return that day.

The following night when my father still hadn't come home, my mother became really worried and said to me, let's break the padlock and look inside the storeroom.
I was also curious what he had hidden inside that he wanted to protect so badly. It was strange that he even went the length of locking it up with a padlock. I removed the padlock and metal fittings.

Inside we found my father sitting on the floor hugging his knees, facing us, with a faint smile and vacant eyes.

Why was the door locked? Why was my father inside?
I am yet to hear a plausible answer from him because he's gone senile since that day.
Today he still sits inside the storeroom, looking at the empty space and laughing happily.