Responses
he is fighting the urge to kill someone for Kirin because that would make him lose him which would be greatly inconvenient since Kirin is his most effective source of enjoyment which outweighs the enjoyment coming from killing(he even said so in one of the chapters) He doesn't do it for Kirin, he does it for himself. Once he gets bored of Kirin he will probably kill him or abandon him. Psychopaths are not capable of love so yeah, Kirin is just a mere obsession.
The fact that Kang Moo’s fighting the urge to kill someone because of Kirin means something. I know that Kang Moo isnt capable of loving someone, but i dont think how he treats Kirin is just a mere obsession.