Sehai Kun
"Sehai Kun, Sehai Kun!"
"What's the matter Kat chan?"
"I was just told my entire existence and world is all a dream, how do I test if it's real or not?!"
"You're so hopeless Kat Chan" a knife was dropped into ground "dream testing device!"
"Eh?"
"Just kill a bunch of people and see if they re-spawn."