how did cain know jooin in the first place? he do be sus af ngl

Remember Cain remember his past life with Jooin that's why he know Jooin. In my theory i think Cain was Jooin's pet(dog) in their past lives (▰˘◡˘▰)

but he said he tricked join?

When he said that he means "When he get an apartment he chose dirty and small room so he can go to Jooin house (so he did it on purpose) and that's why he said" Sorry I tricked you" don't worry Cain is Good and Innocent! ╮(￣▽￣)╭

ohh thank you!