Chapter 3: Secrets and Antidotes
That day, Ao arrived at school a little earlier than usual. The sky was gray, and the damp morning wind typical of late June brushed against his cheeks. The sound of distant construction and birdsong beyond the front gate played a quiet, discordant melody.
As he opened the empty library doors, Ao naturally made his way to the pharmacology section tucked deep in the back. Through the narrow maze of shelves, he found her just as he expected.
Hisui Shirasaki. Her uniform collar was neatly arranged, and just like the day before, she quietly had her book open in front of her.
“…I knew you’d come.”
She spoke without lifting her face, as if she had predicted his arrival. Her voice was calm and matter-of-fact.
Ao sighed and sat across from her.
“I need to ask you something. Please answer honestly.”
Hisui raised her eyes from the page. Deep within them, something flickered.
“You know too much about poison.”
“…”
“I’d understand if you were just interested in it. But you can identify the smell of atropine, name the plants that contain it, and even explain how to neutralize it. That’s… not normal for a high school student.”
Silence fell. The faint hum of the library lights echoed like a heartbeat.
Hisui slowly closed her book, tracing the corner with her finger. After a pause, she spoke quietly.
“My mother was a herbalist.”
The words dropped into Ao’s heart like a dose of poison.
“She ran a small clinic. Had lots of patients. People trusted her. But one day… she was suddenly arrested. They said she poisoned someone.”
“…Was that true?”
“It was in the news. The moment her name appeared online, people threw rocks at our house. They taped papers to our door that said ‘murderer.’ Neighbors stopped talking to us.”
Ao was speechless. Before he could respond, Hisui continued.
“The evidence was unclear. But… there were mistakes in her records. Some of the herbs she used weren’t listed in the ledger. The police saw that as deliberate.”
“…Was she convicted?”
“She got a suspended sentence. She quit medicine. Now she works at a factory in the countryside. She used to be a doctor, but she can’t treat anyone anymore. And every time I transfer schools, I hear the same thing: ‘She’s the poison girl.’”
Her voice was steady, but beneath it was something trembling frustration, anger, and a deep, unanswered question.
“I wanted to understand poison. Whether it really kills people. Whether what my mother did was a crime, or just a misunderstanding. I had to find out.”
Ao clenched his hands atop the desk and looked her in the eyes.
“Are you… using poison at this school?”
Hisui raised her eyebrows slightly, then shook her head.
“No. I haven’t done anything. But… someone has. Someone who knows poison like I do and is using that knowledge to hurt people.”
“Why now? Why at this school?”
“I don’t know. But that last incident that happened to Akiyama-senpai wasn't just a prank. Someone is clearly running an ‘experiment.’ They’re carefully selecting poisons. Choosing ones that only someone who understands both their effects and risks would dare use.”
Ao felt another chill run down his spine.
“Then we’ll investigate.”
“…What?”
“Your mother, and what’s happening now poison can be medicine if used right. So let’s use our knowledge to find the truth.”
Ao spoke with conviction. Then he placed a notebook on the desk in front of her.
Inside were pages filled with what he’d compiled: a quick-reference chart of toxic compounds, a symptom guide by poison type, and clippings from newspaper reports on past poisoning cases.
Hisui turned the pages in silence, until her finger stopped on one particular article.
“This… This reporter covered my mother’s case. I remember the name. Tojo…”
“If that reporter covered other similar cases, maybe there’s a connection.”
They continued researching in the far corner of the library until nightfall.
As closing time approached, Mr. Shimura, the school librarian, a mild-mannered middle-aged man came over to them.
“You two are interested in pharmacology?”
“…Yes.”
“My younger brother used to work at a pharmaceutical company. He researched poison and poisoning incidents. We have some old papers stored in the archive room. I can lend you the key if you want.”
Ao and Hisui exchanged glances.
“Yes, please.”
That night, buried in the archive’s yellowed documents, they found an anonymous report:
“Suspicious use of medicinal herbs detected at a certain high school. Possible signs of intentional poisoning… Multiple perpetrators suspected.”
The handwriting was rough. The date was three years ago. The school’s name: Shirasagi Academy, the same school where Hisui’s mother had been accused.
Ao gasped. Hisui narrowed her eyes in silence.
Just then, a book slid off the far shelf without any wind.
The title read: The Maze of Natural Poisons: Where Medicinal Herbs Cross with Murder.
A theory began to form in their minds.
Someone, over a long period of time, had been trying to expose an unspoken truth using poison. And now, it is happening again.
