private, I, me
私 centers on what belongs to the self: something private or personal. The first-person pronoun senses (I, me) are natural extensions of that self-focused idea.
私 originally combined 禾 (grain) with 厶, which is thought to represent a private or selfish element. The character came to mean private or personal, and later developed first-person pronoun uses in Japanese.
Grain 禾 kept to oneself 厶 is private. Picture a farmer hiding a portion of the harvest for personal use—that's 私, private and me.
For シ, imagine a private stash of grain hidden under a sheet: sheet -> シ, and the sheet keeps the grain private.
I; me
I; me
private (establishment)
private; personal
ordinary clothes (i.e. non-uniform); plain clothes; civilian clothes; casual wear; mufti
private property; personal belongings; personal effects
private life
private (non-governmental) school (college, university)
private railway
public and private matters; official and personal affairs; professional and personal lives
private university
personal use; private use
personal opinion
personal affairs; private matter
private
private ownership
private residence
private enterprise
whispering; private talk; talking (during a class, lecture, etc.)
private expense
post office box
small private school (esp. for cramming)
we; us
private document