Okay, hear me out but old silly lady! MC
Lucifer who got some wrong information about the human they were going to take as a student (cough kidnap cough) for the exchange program.
Everyone is confused when a cute grandmother enters through the portal.
Lucifer perplexed proceeds to ask who she is, what she is doing here and where MC is.
MC: that's me, son. MC. how do you know my name? :D
-… they don't believe it, until they go back to check the documents and notice that the date is around 1970 and MC was around 20 years old at that time.
Diavolo is amused by all this while Lucifer is embarrassed of having made such a big mistake.
Diavolo: Cheerful since you signed the invitation, I can assume you want to study at RAD?
MC:…That wasn't my taxes??
Diavolo: Chuckles
Somehow she ends up being a student…but she doesn't do much studying anyway.
Mammon complains about having to take care of a granny…he ends up getting attached quickly. lol
Unapologetic flirting from the characters towards MC.
MC: shy Oh…aren't you adorable? But I'm very old and you're a very young man.
characters: MC, please. I am hundreds of years older than you--