self
己 centers on the self: one's own person, identity, or ego. It is the core concept of selfhood.
己 is a pictograph of a bent or curved object, possibly a thread or a measuring tool, and came to represent the self through phonetic loan or abstract extension. The exact origin is uncertain.
The shape of 己 looks like a coiled snake or a curved thread, but think of it as a person curled up, focusing inward on themselves. It represents the self.
For コ, imagine a person looking in a mirror and saying 'co' as in 'co-self' (like 'co-pilot' but for self). The sound 'co' cues コ while the person sees their own reflection.
self; oneself
I; me
oneself (itself, etc.)
self-interest
one's own style; self-taught manner
self-control; self-mastery; self-restraint; self-denial
acquaintance
selfishness; egotism; egoism; egocentricity
personal; private; oneself
take care of yourself before you take care of others; wave off your own flies before you wave off someone else's flies
introduction of someone else
exercising self-restraint and conforming to the rules of etiquette and formality
spirit of self-denial
egoism; egotism; selfishness
egoist
egoism; selfishness
selfish; egoistic; self-serving; self-interested
The Selfish Gene (1976 book by Richard Dawkins)
selfish gene
Okuninushi; deity of magic and medicine later viewed as equivalent to Daikokuten and celebrated at Izumo Grand Shrine