open, unfold, unseal
開 centers on the idea of opening something that was closed or sealed: unfolding, unsealing, or making something accessible.
holding (a conference, exhibition, etc.); opening; hosting (e.g. the Olympics)
opening to the public; making available to the public; exhibiting; unveiling; release (of a film, information, etc.); disclosure; publication
start; commencement; beginning; initiation
development; cultivation; application
to open; to undo; to unseal; to unpack
to open (e.g. doors)
development; evolution; progression; unfolding; (plot) twist
to open (a door, etc.); to unwrap (e.g. parcel, package); to unlock
to open out (of a view, scenery, etc.); to spread out; to become clear (of a road, visibility, etc.); to open up
reopening; resumption; restarting
opening (a door, window, etc.); leaving open
raising the curtain
opening; gap
establishment; opening; setting up; inauguration
opening a business; opening a practice
reclamation (e.g. of wasteland); cultivation; development
release (of information, documents, etc.); disclosure; display
opening a new shop
opening (a letter, parcel, etc.); breaking the seal
private; non-public; secret; closed-door; closed
flowering; blooming; blossoming; coming into bloom
opening of a meeting
opening (the doors of a venue)
opening (of a new road, railway, etc.); going into operation (e.g. telephone communication); beginning services
開 combines 門 (gate) and 廾 (two hands), depicting hands opening a gate. This directly conveys the idea of opening.
Picture two hands 廾 pushing open a large gate 門: the gate swings wide, unfolding and unsealing the entrance.
For カイ, imagine a kite caught in the gate; when the hands open it, the kite flies free: kite -> カイ.