But whatever the reason may be, my forgetfulness is not normal. Of that I’m certain.

“But, it’s not like I’m forgetting things because I want to. There’s a sickness in my brain, right? I
can’t help it, so be nice to me!”

“No, I don’t think we can just call it a ‘sickness’ and be done with it…” Matsuda shook his head
slightly. “The human memory is a very complicated thing and there’s a lot we don’t know about
it. It’s almost like… a black box. Your situation isn’t just a simple sickness that can be dealt with
like any other.”

As he explained, he stuck suction pads all over my head and face, the cords from which were
attached to the machines on the trolley.

“There’s a part of the human brain that we call ‘episodic memory’. It stores your personal
experiences― what you see and hear. The area of the brain responsible for it is called the
hippocampus. If something goes wrong there, the brain experiences difficulties in creating and
storing new ‘episodes’. There’s a famous old example about a patient who had the hippocampus
removed in surgery and lost all ability to form new memories. Since then, there’s been a lot of
research about the exact role of the hippocampus in relation to memory. That said, even if your
hippocampus is malfunctioning, you’d still retain your ‘procedural memory’― memory of how
to do tasks, like riding a bicycle or using tools. You won’t remember the episodes related to those
tasks, though. For example, you might remember how to ride a bicycle, but you won’t remember
how you learned to ride them… That’s it in a nutshell.”

“I see… So that’s why even though I’m super forgetful, I still know how to read and write in my
notebook.” I held the notebook in question with both of my hands, and nodded thoughtfully.

Ryoko Otonashi’s Memory Notebook.