Responses
Jooin gave him his email
Cain was Jooins dog in their past life.
In the raws oh Jooin didn't have a good past life so Cain was checking on him to make sure he was happy in this life
remember in the beginning of this, cain knew jooin before jooin knew who he was (or at least acted as if he'd seen him before), he kept calling him master in the airport and somehow even found jooin's email and proceeded to email him everyday until jooin answered. not saying he's a bad guy but he's definitely done some weird things, he's 100% suspicious