The play mainly tells the story of a middle school female teacher who finds her four-year-old daughter accidentally drowned in the campus swimming pool. Later, after a private investigation, she found that it was two classmates who murdered her, but the motive for killing was ridiculous. The teacher who lost his beloved daughter resigned and did not apply to the police for a new investigation. Instead, he confessed the truth to the whole class on the day of graduation and revealed his revenge plan, which planted a fear factor in the students' hearts. When ethics and justice disagree, which side should you choose? The psychological evolution of the murderer and the avenger, in turn, beats our inner moral standards.

Confession is a work of reasoning with conscience. The whole play takes the first person as the background. The murderer is ridiculous, but there are social reasons. The Avengers are cruel, but they are intended to warn the world. There are not many characters in the story, but the pattern is very large. There are many paragraphs and angles, but the narrative efficiency is very high. Compared with many stories that emphasize the strangeness of killing methods, this is a good story that really pays attention to reality and does not conform to the routine. From a priest to a missionary, Moriguchi never simply understood goodwill. In her cold and desolate heart, the world is like a classroom in a movie, dark blue and lead. So in this small world as familiar as a blackboard, she began to tell the truth.