**Story Core**:
In the summer of 1998, an eight-year-old boy named Song Zhi drowned by the river in his hometown. The bloody hairpin of a strange girl was wrapped in chocolate wrappers left at the scene. Ten years later, police academy graduate Song Shiwei reopened the case and discovered that the wrapping paper concealed a fluorescent code - each crease was a "childhood eulogy" carefully composed by the serial killer Li Mo.
**Character Map**:
? **Song Shiwei**: The criminal policeman who is burdened with the guilt of "killing his brother" can smell the residual warmth of emotion from the folds of physical evidence. He always dissects firefly corpses late at night, trying to decipher the Morse code left by the murderer from bioluminescence.
? **Shen Yu**: A physical evidence expert who comes from a family of forensic doctors. He has a binary coded "shimmer" color value tattooed on his left arm. As a boy, he used circuit boards to imprison fireflies, and as an adult, he used a scalpel to cut open the cocoons of sin.
? **Li Mo**: A high school biology teacher during the day, and a "firefly collector" at night. A specimen of Sophora japonica was buried in the victim's stomach, an altar was made from the soil of his mother's grave, and the age badges of twelve children were tattooed on his chest.
Conception:.