to open an ulcer or sore
殨 centers on the breaking open of a sore or ulcer, specifically the act of an ulcer bursting or being lanced.
殨 combines 歹 (death, decay, or injury) with 貴, which likely contributes the sound. The exact historical development is uncertain, but the structure suggests a phono-semantic compound related to bodily decay or rupture.
The left side 歹 suggests something decaying or injured, and the right side 貴 looks like a container with valuables. Picture a festering wound that finally bursts open, releasing its contents.
For カイ, imagine a doctor saying 'Kai, we must open this ulcer now!' as they prepare to lance it: Kai -> カイ.