Kanna sneaking into the school library at night to investigate a rumor about a ghost. While she’s trying to look around and prove the story, she unexpectedly meets Chuzenji-sensei there. Instead of being scared, Chuzenji calmly talks with her and starts explaining the mystery behind the supposed ghost. Their meeting becomes the start of the story, showing how Chuzenji helps students understand strange supernatural rumors in a more logical way.