Humans will all die someday.

I had never really thought deeply about such an obvious fact.

The spring of my second year in high school. I met a certain philosophy teacher.

Hokuto Matsumura. A teacher who was a bit cold, used difficult words, and was impossible to read.

But for some reason, I liked the philosophy room where he was.

When classes ended, I would head there for no reason at all.

"Sensei!"

"...You're here again?"

Those casual exchanges eventually became a precious time for me.

Sensei doesn't know.

That I am living while counting the time I have left.

And I didn't know yet, either.

That this encounter would greatly change both Sensei's loneliness and my life.