Defeated all opponents in Pom! Pom! Party!

Clear Chapter 4.

Completed Chapter 4, 'Crossbell's Fate.'

Use the Love Key to spend the night with a student.

Completed Chapter 3, 'Budding Turmoil.'

Collected all orbal car customization options.

Collected all decorations and Enigma covers.

Clear Chapter 2.

Completed Chapter 2, 'The West Zemuria Trade Conference.'

Achieve the highest level bond with someone.

Unlock new areas inside the academy.

Present false evidence.

Find a hidden Monokuma.