"Mukuro-sama would know if they're lying, byon," Ken says stubbornly. "And I can smell when people are lying!" This is...something of an exaggeration, although it's true that Ken's senses and instincts are sharp. Even if he doesn't know much about first aid, much less complex medical procedures, it'd be hard for a doctor to get even a necessary one past him, much less convince Ken that something harmful was safe and required. "Besides, if they did anything bad to you, I'd rip 'em to pieces, byon. I don't think they're that stupid."