What am 'I'?

Murakami, you seem to be a very wise man, and I was hoping to see if you could help me with figuring out what I am.
I've become a bit obsessed with finding a proper answer to what 'I' am. Am I my brain?  My personality? My thoughts? Most people would probably say it's a combination of all such factors, but I can't be satisfied with such an answer. I have to find out exactly what it is 'I' am, but nothing I read seems to get me closer to the answer.
(Gulgom、男性、23歳、IT Technician)

Dear Gulgom,

Basically I am thinking of myself as a kind of aggregate of the various functions. I am just like an onion. I have many functions. If I peel off those functions one by one, what is to be left as my core? Nothing, I suppose. That would be nice, don't you think? I think so, anyway.