3 Nen A Kumi: Ima kara Mina-san wa, Hitojichi Desu - Season 1

10 days left until graduation which was supposed to be a quiet, easy, celebratory moment in the students' lives ... but instead their homeroom teacher sets off an explosion in the school and takes them hostage in an effort to find out the truth of a student who recently died.

Still in shock after the death of a classmate, their teacher gives them another task. If they fail: someone else will die. If they succeed, everyone will live another day. The task is to find who published a video online that could have led to Reina's death.

The third day in, Hiragi gives a new task only this time it's for the detective. They have to find who recorded the video in the first place. Though this task holds much more weight as he is threatening to kill five students should the detective fail in his mission but if he succeeds, he will let all of the students go.

On the fourth day, Hiragi gives the new task of finding who told the student who confessed to taking the video. However, when someone actually raises their hand to confess -- it's a surprise to the students who it is. But now the student who confessed is tasked with telling who edited the video or 10 students will be sacrificed.

With Hiragi unconscious, the students take the opportunity to try and escape. They end up finding out a secret that Hiragi tried to keep from them. This shines new light on the bigger picture and how they could help if they truly wanted to. But it divides the students, half want to help but the other half want to escape.

This time the task that Hiragi gives out is for the teachers! Among one of them is the person who wanted the video of Reina edited so that it would ruin her. Which teacher will it be? The consequence this time if they fail is that he will blow up the entire class.

The culprit is named! But they need evidence. All of the students are shocked at the video and who Hiragi said was behind the video being edited, all discussing and talking among themselves to wonder if it is the truth or not. Some have a hard time believing him and go as far as to turn to violence. However when Hiragi and the teacher who committed the crime meet up -- something is revealed.

Hiragi has a dream and tells Kayano Sakura about it. Hiragi tells the students how the evidence they have found so far has led to this moment, which starts the real work. That what was revealed before wasn't all there is to the story. Today's challenge is self-study, for the students to spend their time however they like. And with this he gives back their belongings. However -- one of the students finds out something that they hesitate to tell the others.

In this episode, We see the future of the students as well as the past as the story is quickly unfolding. Hiragi takes the detective to the roof of the school. Kayano Sakura confesses to something she has been hiding all along. 

Hiragi decides to reveal everything on a live broadcast on the tenth day and gives a very emotional take on why he believes Reina truly died. Kayano Sakura fears what Hiragi will do after remembering the dream he had told her about. The students try to make their way to the rooftop before what Kayano fears might happen.