The Mafia Teacher
When you have a color changing octopus nicknamed Korosensei, government agent Karasuma, and a assassin named Irina Jelavich, all teaching E class, who else could you add?
A Italian Mafia boss, anyone?
Tsunayoshi Sawada, Vongola Decimo.
The world governments must be worried if they resort to contacting the Vongola, the world's strongest Mafia. For them to ask for the mafia to send a teacher they must be insane.
So with Reborn's fedora being jammed on his head by it's owner, Tsuna sets out to teach a class of middle schoolers.