Binoculars

(Translated from Japanese by Saya)
I had a strange hobbie.
After midnight I would go up on the rooftop of my house and, using binoculars, observe the town where I lived.
I took joy in looking at the quiet town, so different from how it was in daylight.
Huge water tanks in the distance, a taxi going up the hill with a drunken customer, or a solitary vending machine glowing in the darkness - all such things somehow excited me.

To the west of my house there was a long, steep hill which went straight down to my house.
So when I looked to the west, the entire hill easily came into view.

I was looking at a vending machine placed on the hill with binoculars, thinking something like "oh, a huge moth is flying around it," when I noticed a guy rushing down the hill like there was no tomorrow.

"What was that?"
I refocused my binoculars, and it turned out that the person was a naked, skin-and-bones childish-looking guy, with a broad smile on his face, who was waving madly at me while he ran towards my house at breakneck speed. 
He clearly acknowledged my presence, and moreover he was looking at me straight in the eyes.

For a few seconds, I was too stunned to move, but I had a hunch that something really terrible was about to happen, and quickly ran down the stairs to go back inside the house.

"Oh shit! What was that? What was that? What am I gonna do?"
After I had closed and locked the door, I became totally panicky and terrified.

Then I heard the sound bam bam bam bam bam and realised that the guy had just ran up the stairs to the rooftop. He was clearly looking for me.
"This is really bad. What am I gonna do? What am I gonna do? Really, what the hell is it?" So on and on I kept thinking in my mind while I stood in the middle of the sitting room with a steam iron (weapon) in my hands and prepared myself for whatever was about to come.

Soon, I again heard him go bam bam bam bam bam bam  as he ran down the stairs.
I was shaking like a leaf and thought I would go mad from fear, when the door went Bang Bang Bang Bang Bang Bang Bang!! and the doorbell rang Ding-dong ding-dong! Diiiing-dong! Ding-dong !!
Not only that, he was groaning like, "Argh! Hummmm! Argh! Hummmm!"

My heart skipped a beat and then began to race and pound like it was about to burst.
Even though my body shook violently, I tried to hold my breath as best I could.
Some ten seconds later, the knocking, doorbell and groaning all came to a halt, and it returned to the usual silence.

But I stood rigid and held on to the steam iron until the dawn broke.
What on earth was that guy?