Suspecting the possibility that a killer is at the same school, detective Chu Ja-young (Shin Eun-kyung), with her rookie partner Kim Dong-wook (Eric Mun) search the school to find identical handwriting that matches that of the diary excerpts. When they finally find the matching one, they're told that Jin-mo, the student who wrote the text, had already died in a car accident one month ago.
The passage describes a scenario where a detective suspects a potential killer within a school setting and finds evidence through handwriting analysis. This evidence is later revealed to be false due to the death of the suspected writer, Jin-mo.