3 Nen A Kumi: Ima kara Mina-san wa, Hitojichi Desu S01E04 - Episode 4

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.