Gakuen Alice - Season 1 Episode 15 Let's Go Back to the Academy

Mikan manages to get in contact with the school through the communication device (panda shaped headphones) Hotaru gave her. As Natsume burns through the ropes tying him Narumi gives the three instructions. But Natsume's Alice alerts Reo to their awakening and he takes the device away from them. He has his own conversation with Narumi, and it seems Reo and Narumi were friends at school along with "that person". After he destroys the device Leo sets out to find what type of Alices Mikan and Sumire has. When Mikan isn't affected by his Alice Reo learns that she has the nullification Alice. Leo is shocked and has an investigation done on "that person." After Reo and his men leave Natsume tells the other two to escape. As the two make a run for it Natsume threatens Reo that he will blow up the warehouse if he tries to pursue them. Mikan realizes while running that Natsume isn't bluffing and that he really intends to blow himself up. Mikan runs back and stops Natsume just in time.