The Orb of Destiny was a metallic object with a seamless, intricately circular shape.
Humanity was at a loss as to how to use the sphere, but with the help of aliens, they succeeded in connecting the human network with the sphere of destiny.
And that machine was called the butterfly effect.
Using the butterfly effect, humans have been able to detect small events that can lead to big events.
In other words, we can find the first wingbeat.
…
Here, the butterfly effect, a gift from aliens, finds the person who started this incident by spitting out the gum and sends a text message.
---From "The Butterfly Effect"

20 years ago.
I was such a terrible kid.
At that time, I was dropping junk from the roof of my apartment toward the ground.
What on earth was so funny about that? I don't even remember.
What I remember is, a mess
It is said that there was an iron ball among the sand.
The iron ball that left my hand fell straight down and hit the head of an old man coming out of the apartment.
The old man collapsed on the spot like a toy, and I was so shocked by the sight that I quickly ran back home and hid.
Because it felt like the old man would wake up at any moment and come up to the rooftop to catch me.
That never happened.
The old man never got up again.
At that time, I was hiding in my room, worried that the old man would find out.
Crazy kid.
---From "I'm a really terrible kid"

Now, even Kim Nam-woo's sense of smell is shared by people.
During that time, Kim Nam-woo spent most of his time with his eyes closed.
I put earplugs in my ears.
I hated seeing those damn people having fun.
I didn't want to give you even a little bit of a story to tell.
Sometimes, I've even read difficult medical books for hours on end, deliberately trying to be boring.
The more this happened, the more monotonous Kim Nam-woo's life became.
Going out has also almost disappeared.
I spent most of my time lying down and avoided pleasant things as much as possible.

---From "Kim Nam-woo's Boredom Killer"