In episode 4 of "Nanatsu no Maken ga Shihai suru," the story unfolds in a classroom where Katie Aalto, a student, is mocked by her classmates for her interaction with a troll. Despite the ridicule, Katie continues to approach the troll with kindness, feeding it and attempting to communicate with it. Her friends Guy, Nanao, and Oliver defend her when the mockery escalates into a brawl in the classroom.

The situation intensifies when Mr. Andrews challenges Oliver to a duel. Instead of a traditional duel, Mr. Andrews proposes a goblin hunt, where the winner is the one who slays the most goblins. The game takes place in a coliseum, and the students are spectators. However, Nanao and Oliver refuse to participate in the cruel game, leading to a confrontation with Mr. Andrews and the other students.

In a sudden turn of events, a Garuda, a divine beast, is released into the coliseum. The students panic, and the coliseum doors are sealed, trapping everyone inside. Nanao and Oliver decide to fight the Garuda to protect their classmates. Nanao, the daughter of a samurai, bravely confronts the Garuda, while Oliver uses his magic to create openings for her.

Meanwhile, the other students, including Katie, Guy, and Chela, are protected by a wind barrier erected by Mr. Andrews. Despite his earlier hostility, Mr. Andrews demonstrates his skills as a magician and his willingness to protect his classmates.

At the climax of the episode, Nanao and Oliver succeed in defeating the Garuda, with Nanao delivering the final blow. They are injured in the process, but their classmates, including Mr. Andrews, come to their aid.