Why is everyone saying cain is sus?? Am i missing something here??

you probably overread the part where he said to himself that he's lying to jooin. he actually speaks korean very well even though he pretends to be bad at it. anyways he's having some kind of motives

At the end of chapter 31 Cain said “I’m sorry I tricked u jooin” so it probably means he wasn’t reincarnated in his last life, knows fluent English or he’s guilty of lying about not having a home

I mean Korean