crooked mouth, evil, dishonest
咼 centers on a distorted or crooked mouth, which extends figuratively to evil or dishonest speech and character.
咼 combines 冎 (a bone or skeletal shape) with 口 (mouth), suggesting a mouth that is crooked or distorted like a bone. The exact historical development is uncertain, but the component combination likely depicts a physical deformity used metaphorically for evil or dishonest speech.
The outside 冎 looks like a twisted bone, and inside is a mouth 口. Picture a mouth twisted like a crooked bone, speaking evil and dishonest words.
For カイ, imagine a sly character named Kai with a crooked mouth whispering lies: Kai -> カイ, and his mouth is twisted with dishonesty.