Finding Avalon: The Quest of a Chaosbringer Volume 3 by Akito Narusawa

The Battle of the Classes draws near, and students must compete inside the dungeon for a weeklong exam to prove their superiority. Rising above their past defeats at the hands of the elitist bullies of the upper classes, the brave Class E students devise a cunning game plan to maximize their odds.

Luckily, they have a secret trump card—Piggy, the overweight and overpowered former villain. His orders are “Tag along with the upper classes, and try not to embarrass us!”

This is perfect for Piggy, not being a fan of the limelight! He can use this opportunity to get to meet the diva of class A, his game-era crush, as well as share diet tips with a newfound armored friend—but a spy in his class is determined to unearth his secrets. That’s the least of his problems, as the mastermind of Class B threatens the students of every class.

Little does Piggy know that his greatest battle awaits him!