It's the Phantom Thief! - Devilgram
"He's so bad at it lol."
To Mammon's relief, the extreme measures only involve bribing him with one of Levi's greatest treasures: the Thunder Goblet that MC offers to hand him over if he lets Levi and MC alone. Right after MC gives him the goblet, Mammon leaves with what Levi reveals is only a fake goblet, bought on Akuzon, to exchange it for money. Levi then remembers that his anime is about to start and tells MC to stop role-playing as phantom thieves, so he can watch the anime.