The reason why she calls Jin this way, is because Jin is older than her, and she is still a Student at the Mishima Polytechnical School (the one Jin studied once), funniest thing of all is that he tells her to stop calling him Mister (which means Senpai anyways) in one of his victory pose against her.
Really funny how she pretends to have this fake sweet and admiration personality for deceive , since everyone expects such a young girl to have be one when in reality she's a monster, hold your horses jin she may call you senpai but that's your auntie she owns you new eves money 😂
