Identity Time

Identity Time (素性の時間, Sujō no jikan) is Extra Chapter 3 of the Assassination Classroom manga.

Short summary
While the assassins discussed their plan on how to rescue Azusa, Korosensei noticed Hotaru holding up a knife, announcing she wanted to save her mother as well. Putting away the knife, Korosensei told that he admired her courage, but for now it would be better for her to observe what the assassins will do. After a short amount of time, Seeker managed to find the location of Sengoku. While observing the quartet, Korosenei explained to Hotaru that Seeker was once an air traffic controller who lost his job in the wake of a plane crash, but later decided to use his acquired knowledge for other means. Seeker further detailed that Sengoku was a loan shark who exploited clients with large, unpayable debts. At the same time, Azusa was being forced to sign a contract that allowed Sengoku to rape her. With no other choice, she signed the contract.

Once Chantha used a master key to unlock the front door, Korosensei and Hotaru were told to stay put. In the nick of time before Sengoku can abuse Azusa, the assassins barged into his room and engaged combat with his men. At the same time, Korosensei told Hotaru that the quartet originally worked at legitimate careers before becoming unlucky. Hotaru then asked how he knew so much, to which Korosensei responded that he was in the same line of business as them, but found more fulfillment in another career. Eventually, the assassins incapacitated every goon in the room, save for Sengoku. In defense, former boasted that he had the support of a yakuza clan and that he had a legitimate contract with Azusa. As a response, Futoshi, using his knowledge in law stated that the terms listed were all illegal, and if he were to go to trial, the yakuza would let Sengoku take the blame. Sengoku hung his head in defeat, and reluctantly allowed Azusa to go free.

After everyone watched Azusa and Hotaru reunite, Korosensei told the assassins to bring Hotaru with them outside. While they reluctantly do so, the assassins wondered if they could help people in a legitimate line of work. Once they were gone, Azusa remarked how they almost ruined her plan, and detonated a bomb hidden in her cleavage.