Monster Movie Still 5 of 11

What exactly is a "monster"? What do we see at the end of each character's search for the "monster"? Little Minato starts acting strange. His mother senses that something has gone wrong. When she discovers that a teacher is responsible for her son's behavior, she storms into the school in search of enlightenment. The story is told from the mother's, teacher's and child's point of view; the truth gradually emerges.