Hajime making his grand debut as "Kasugano" during the Practical Exams Arc by hijacking the broadcasting system and calling out Hope's Peak for its horrendous criminal activity.
Hajime exposing Kanade for what she really is during the Concert Arc. She arrogantly confesses her crimes to him, thinking that she'll soon kill him and escape, only for it to be revealed that Hajime had been using a microphone in his tie to record the whole thing and, with Chiaki's help, broadcast it to the entire mall via the speaker system.
Following this, Kanade decides to murder Hajime anyways and chases him through the parking garage they were in. Hajime, however, saw this coming and set it up so that Kanade would be exhausted when she had to face off with her true opponent, Sonia, who swiftly gives her a No Holds Barred Beat Down.
The Quantum Crew taking part in the Storm Arc and showcasing their unique teamwork and fighting skills.
Kotoko disowning her father also deserves a mention.
Kotoko: Im gonna let you live with this! Were gonna turn you over to the police and youre going to spend the rest of your life rotting in prison, thinking about how all of this is your fault and you have nobody to blame but yourself!
Junya: But But Kotoko, were family!
Kotoko: No. Were not. I have a real family now, and its not the name Utsugi, thats for sure. You tried so hard to break me, but you couldnt. I beat you. You cant hurt me anymore, so what will killing you accomplish for anyone? Lucky you, Utsugi Junya. You get to live with that. Goodbye. Forever.