Keyword
connected to
Info
FrequencyTop 100-200
Type
Kyōiku (4th grade) 
?
Shinjitai ?
KankenLevel 7
Heisig2173
Old form關
Readings
かん
(86%)
かか
(11%)
せき
(1%)
Composed of
gate
horns
heaven
Mnemonic

It's a gate that is connected to both heaven and hell through a pair of demonic horns.

Used in vocabulary (793 in total)
relation; relationship; participation; involvement; influence; effect
unrelated; irrelevant; unconcerned; unconnected
to be involved (in); to get involved (in); to relate to (a matter); to pertain to; to (seriously) affect; to concern
Examples (200 in total)
That kind of relationship is still continuing even now.
So it does have something to do with it.
It had nothing to do with me.