A young man commits suicide and his father holds his son's classmates hostage in order to find out why.
While eating lunch one day, Touru Kotake casually asks his friends, Daiki Senkawa and Kaname Nojima if they have ever thought of jumping in front of a train before. All of them laugh and say that they don't have any desire to commit suicide. Touru clarifies his question, saying that he's not asking if they've thought about suicide but is asking about the desire to jump and the feeling that would create. All of them deny having these thoughts, but later that day Daiki commits suicide by jumping from his apartment building.
Later, Daiki's father holds the class hostage, demanding to know what pushed his son to commit suicide. In the middle of the ordeal, Touru receives a shigofumi from Fumika and reads it aloud. In it, Daiki states that actually had considered what Touru mentioned. He says that he had no desire to die, although he had no special desire to live either, and simply wanted to know what it felt like to jump. He concludes by saying that nobody should take blame or feel responsible for his actions, for it was something that he did on a whim.
Daiki's father doesn't accept this answer but the police throw a flashbang into the classroom and apprehend him, ending the ordeal without any injuries or deaths.